ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • General Chemistry  (643)
  • Humans  (586)
  • Cell & Developmental Biology  (273)
  • 1995-1999  (1,502)
  • 1945-1949
  • 1998  (1,502)
Collection
Keywords
Publisher
Years
  • 1995-1999  (1,502)
  • 1945-1949
Year
  • 101
    Electronic Resource
    Electronic Resource
    Mesomorphic Cyclometalated (Cyclopentadienyl)palladium and -platinum Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 501-504 
    Details
    ISSN: 1434-1948
    Keywords: Metallomesogens ; Azo compounds ; Palladium ; Platinum ; Cyclopentadienyl complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mesogenic 4,4′-bis[4-(n-octyloxy)benzoyloxy]azobenzene (HL) ligand reacts with [(PhCN)2PdCl2] to give the dinuclear cyclometalated complex [(μ-Cl)(L)Pd]2 (1), from which the mononuclear half-sandwich [(η5-C5H5)(L)Pd] (2) species has been obtained by reaction with Tl(C5H5). The PtII analogue of 2, [(η5-C5H5)(L)Pt] (4), has been prepared in a similar manner starting from [(μ-Cl)(L)Pt]2 (3). Both dinuclear complexes 1 and 3 display a smectic C phase (SC) stable over 80°C. Whereas 4 is the first example of an 18-electron PtII mesogen, both mononuclear 2 and 4 are mesomorphic materials that exhibit a nematic phase spanning a wide temperature range.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 102
    Electronic Resource
    Electronic Resource
    Rearrangement of Bis(dimethylamino)bis(1-indenyl)diborane(4) into Bis(dimethylamino)bis(3-indenyl)diborane(4) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 505-509 
    Details
    ISSN: 1434-1948
    Keywords: Chlorobis(dimethylamino)(3-indenyl)diborane(4) ; Bis(dimethylamino)bis(1-indenyl)diborane(4) ; Bis(dimethylamino)(1-indenyl)(3-indenyl)diborane(4) ; Bis(dimethylamino)bis(3-indenyl)diborane(4) ; Rearrangement ; X-ray structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Indenyllithium reacts with dichlorobis(dimethylamino)diborane(4) with formation of bis(dimethylamino)bis(1-indenyl)diborane(4) which rearranges on heating to the isomer bis(dimethylamino)bis(3-indenyl)diborane(4). The „mixed” bis(dimethylamino)(1-indenyl)(3-indenyl)diborane(4) is obtained from indenyllithium and chlorobis(dimethylamino)(3-indenyl)diborane(4). The main structural differences between the two isomers 3 and 4 are a slightly shorter B-B bond in 4, as well as a stronger twist about the B-B bond (89.9° vs. 67.4°) and, as expected, a shorter B-C bond. There is, however, no significant B-C π bonding.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 103
    Electronic Resource
    Electronic Resource
    Synthesis and Structural Characterization of Gold(I) and Silver(I) Complexes of the Multidonor Ligand 2-(Phenacylthio)pyridine - Crystal Structures of [(AuPPh3){py{SCH2C(O)Ph}-2}](ClO4) and [(AgPPh3)(OClO3){py{SCH2C(O)Ph}-2}] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 511-516 
    Details
    ISSN: 1434-1948
    Keywords: Gold(I) ; Silver(I) ; S-donor and N-donor ligand ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand properties of 2-(phenacylthio)pyridine towards gold(I) and silver(I) have been investigated. From the reactions of the ligand with acetone solutions of [M(PPh3)(acetone)]ClO4 (M = Ag, Au) under various experimental conditions, complexes [(AuPPh3)n{py{SCH2C(O)Ph}-2}](ClO)n, and [(AgPPh3)n(OClO3)n{py{SCH2C(O)Ph}-2}](n = 1-3) have been obtained. The crystal structures of the complexes [(AuPPh3){py{SCH2C(O)Ph}-2}]ClO4 and [(AgPPh3)(OClO3){py{SCH2C(O)Ph}-2}] have been determined by X-ray diffraction. In the cationic gold complex the metal is linearly coordinated to nitrogen and phosphorus, whereas the corresponding silver complex displays a trigonal planar geometry with pyridine, phosphane and perchlorato ligands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 104
    Electronic Resource
    Electronic Resource
    Oligomeric Solvent-Free Magnesium Bis(phosphanides) - Molecular Structure of Trimeric Magnesium Bis[bis(trimethylsilyl)phosphanide] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 517-521 
    Details
    ISSN: 1434-1948
    Keywords: Bis(silyl)phosphanes ; Magnesium ; NMR spectroscopy ; Oligomers ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metathesis reaction of (dme)LiPH2 and chlorodiisopropylsilane yields HP(SiHiPr2)2 (1) and P(SiHiPr2)3 (2). The metalation of 1 by n/sec-dibutylmagnesium in heptane leads to the formation of dimeric magnesium bis[bis(diisopropylsilyl)phosphanide] [(3)2]. A toluene solution of magnesium bis[bis(trimethylsilyl)phosphanide] (4) shows a dimer-trimer equilibrium in the 31P{1H}-NMR spectrum at -40°C with an increasing amount of the dimer with increasing temperature. A molecular mass determination by freezing-point depression in benzene yields a value of 516 g·mol-1, which lies between a monomeric and a dimeric molecule. Cooling of the toluene solution to -30°C leads to the precipitation of single crystals of monoclinic {(Me3Si)2P-Mg[μ-P(SiMe3)2]2}2Mg [(4)3].
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 105
    Electronic Resource
    Electronic Resource
    The “Coloring Problem” in Solids: How It Affects Structure, Composition and Properties (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 523-536 
    Details
    ISSN: 1434-1948
    Keywords: Quantum chemistry ; Intermetallic compounds ; Transition metal cluster compounds ; Crystallography ; Electronic structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The “coloring problem,” as applied to the field of solid state chemistry, addresses the issues of structural preference as well as the distribution of different elements within a given structure. Both the connectivity and arrangement of elements in a solid affect physical and chemical properties, so a clear understanding of the forces controlling how elements will arrange themselves in a solid state structure creates the ability to predict structure-composition-property relationships. There are two fundamental energetic contributions that influence how elements in a structure order: the site energy and the bond energy. This review examines how these two parts of the total electronic energy work together to influence the observed structures, compositions, and properties of intermetallics and transition metal cluster compounds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 106
    Electronic Resource
    Electronic Resource
    Carbonyl and Benzene Complexes of Lithium: Transition-Metal-Like Behaviour of Lithium in Organolithium Compounds (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 537-541 
    Details
    ISSN: 1434-1948
    Keywords: Lithium ; (Benzene)lithium complex ; (Carbonyl)lithium complex ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes of CO and aromatic compounds were believed to be an exclusive domain of transition metals caused by their ability of backbonding to these ligands. But recently, (benzene)lithium and (carbonyl)lithium complexes were characterized by X-ray structure analysis and IR spectoscopy. In order to determine geometries of the complexes and the bonding energies of the benzene and CO molecule to the organolithium starting compound suitable models were chosen in combination with high-level ab initio calculations. For the carbonyl derivative a reaction enthalpy of -8 kcal/mol was found while the interaction with benzene reached unexpectedly -21 kcal/mol. This underlines the ability of lithium to act like a transition metal in subcoordinated organyl compounds without having d orbitals available for bonding.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 107
    Electronic Resource
    Electronic Resource
    Synthesis of the First Lanthanoid(II) Pyrazolate Complex by Redox Transmetallation from Thallium and Mercury Reagents (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 543-545 
    Details
    ISSN: 1434-1948
    Keywords: Lanthanoid(II) complexes ; Ytterbium ; Thallium ; η2-Pyrazolate complexes ; Diphenylmercury ; Redox transmetallation ; X-ray crystal structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ytterbium metal reacts with thallium(I) 3,5-diphenylpyrazolate, or with diphenylmercury and 3,5-diphenylpyrazole (Ph2pzH) in tetrahydrofuran or 1,2-dimethoxyethane (DME) giving, after appropriate isolation, the first lanthanoid(II) pyrazolate complex, [Yb(Ph2pz)2(DME)2]. The molecular structure reveals eight coordinate ytterbium(II) with two cisoid η2-3,5-diphenylpyrazolate and two chelating 1,2-dimethoxyethane ligands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 108
    Electronic Resource
    Electronic Resource
    A Unique Copper-Controlled Template Synthesis of Tetradentate N4-Donor Ligands and Their Propeller-Type Linear Trinuclear CuII Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 547-549 
    Details
    ISSN: 1434-1948
    Keywords: Copper ; Trinuclear ; Formamidines ; Magnetism ; Crystal structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In situ reaction of CuII triflate with aminopyridine or aminopyrimidine and triethylorthoformate in ethanol results in unique linear trinuclear CuII complexes with the general formula [Cu3(L-)4](CF3SO3)2(EtOH)x (L = dehydronated ligand N,N′-bis(pyridine-2-yl)formamidine or the new ligand N,N′-bis(pyrimidine-2-yl)formamidine). The structure [Cu-Cu-Cu angle 175.19(2)°] consists of four nearly flat molecules of the ligand which contribute to the propeller-type structure around the Cu-Cu-Cu axis. A strong antiferromagnetic interaction between the CuII ions is observed, resulting in an S = 1/2 ground state below 100 K.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 109
    Electronic Resource
    Electronic Resource
    Octanuclear Bis(triple-helical) Metal(II) Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 559-563 
    Details
    ISSN: 1434-1948
    Keywords: Metal(II) complexes ; Octanuclear complexes ; Supramolecular chemistry ; Zinc ; Cadmium ; Manganese ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of H2L1 and H2L2 with divalent metal ions leads to octanuclear bis(triple-helical) metal(II) complexes of the general composition [Zn8O2L26] (3) and [M8O2L16] (4: M = Cd2+; 5: M = Mn2+). NMR studies of the diamagnetic cadmium complex 4c show six equivalent ligands. Unambiguous characterisation of 5b was achieved by X-ray crystallographic analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 110
    Electronic Resource
    Electronic Resource
    Formation of Metallocene-Stabilized Planar-Tetracoordinate Carbon Compounds by a Protonation Route (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 551-558 
    Details
    ISSN: 1434-1948
    Keywords: Planar-tetracoordinate carbon ; Zirconocene ; Acetylide complex ; Selective protonation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(alkynyl)zirconocene and -hafnocene complexes 4 react with (butadiene)zirconocene or -hafnocene, respectively, to yield the binuclear σ,π-acetylide bridged complexes [(Cp2M)2(μ-C≡C-R)2] 7 (M = Zr, Hf; R = CH3, C2H5, or CH2Ph). The complexes 7 are selectively protonated upon treatment with N,N-dimethylanilinium tetraphenylborate or tetrakis(pentafluorophenyl)borate to yield the dinuclear metallocene cation complexes [(Cp2M1)(μ-RCC1-H)(μ-C≡C-R)M2Cp2+] 13 (M1 = M2 = Zr, a-c; M1 = Zr, M2 = Hf, h; M1 = M2 = Hf, i) that contain a planar-tetracoordinate carbon atom (C1-H) bearing a hydrogen substituent. Complex 13a was characterized by X-ray diffraction. It reveals an agostic interaction of the C1-H moiety with the M2Cp2 unit. The planar-tetracoordinate carbon unit C1-H of 13a exhibits 13C/1H NMRchemical shifts of δ = 161.0 and -0.11 and a coupling constant of 1JCH = 103 Hz. Selective protonation of (μ-alkynyl)bis(group 4 metallocene) complexes containing other additional bridging ligands provides a rather general synthetic entry to planar-tetracoordinate carbon containing complexes of this type: [Cp2M1(μ-C≡C-CH3)(μ-Cl)M2Cp2] (10a-c, M1, M2 = Zr, Hf) and[Cp2M1(μ-C≡C-CH3)(μ-CH3)M2Cp2] (11a,b) selectively add a proton from [(HNMe2Ph)+(BAr4)-] at carbon atom C1 of the acetylide ligand to yield the corresponding “anti-van′t Hoff/LeBel complexes” [Cp2M1(μ-CH3CC1-H)(μ-X)M2Cp2+] (13d-g and k, X = Cl, CH3), respectively.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 111
    Electronic Resource
    Electronic Resource
    Syntheses of 3-Phenyl-2H-Azaphosphirene Chromium and Molybdenum Complexes - First Evidence for Reaction Intermediates (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 571-574 
    Details
    ISSN: 1434-1948
    Keywords: Phosphorus heterocycles ; 2H-Azaphosphirene complexes ; Carbene complexes ; Chromium ; Molybdenum ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 3-phenyl-substituted 2H-azaphosphirene pentacarbonylchromium and pentacarbonylmolybdenum complexes is reported. New information on the rearrangement cascade, which finally leads to 2H-azaphosphirene ring formation, has been obtained through isolation of a reactive intermediate. A comparison of the 13C-, 15N-, 31P-NMR, and UV/vis spectroscopic data and single crystal X-ray structural data of 3-phenyl-substituted 2H-azaphosphirene chromium, molybdenum, and tungsten complexes is presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 112
    Electronic Resource
    Electronic Resource
    A New Class of Oligonuclear Platinum-Thallium Compounds with a Direct Metal-Metal Bond - 3. Unusual Equilibria in Aqueous Solution (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 565-570 
    Details
    ISSN: 1434-1948
    Keywords: Equilibrium ; Metal-metal bond ; Stability constants ; Platinum ; Thallium ; NMR ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new series of four binuclear platinum-thallium cyano compounds containing a direct and unsupported by ligands metal-metal bond has been prepared in aqueous solution. These compounds are represented by the formula[(NC)5Pt-Tl(CN)n-1](n-1)- (n = 1-4 for compounds I, II, III IV, respectively) and [(NC)5Pt-Tl-Pt(CN)5]3- (for compound V). The oligonuclear complexes are synthesised according to the reaction mPt(CN)42- + Tl3+ + nCN- █[PtmTl(CN)4m+n]3-2-n. Thus, there occurs a change of the coordination number of the Pt center from four (square planar) to six (octahedral). Consequently, the formation of binuclear platinum-thallium cyano compounds involves at least two steps: (i) formation of metal-metal bond and (ii) formation of (NC)5Pt- unit by a cyanide transfer process. - The complexes exist in an equilibrium, which also includes the parent complexes Pt(CN)42- and Tl(CN)n3-n (n = 0-4), and can be controlled by varying the cyanide concentration and/or pH of the solution. The stability constants of the compounds βN =[PtmTl(CN)4m+n3-2m-n{[Pt(CN)42-]m · [Tl3+] · [CN-]n} have been determined by means of multinuclear NMR (195Pt, 205Tl): logβN = 19.9±0.4, 30.7±0.3, 38.6±0.3, and 44.8±0.2 for I, II, III and IV(m = 1, n = 1-4), and 32.1±0.3 for V(m = 2, n = 2), respectively, (in 1 M NaClO4 as ionic medium, at 25 oC). To our knowledge, the present work constitutes the first detailed equilibrium study of metal-metal bonded compounds; it indicates that also other cluster formation reactions described in the literature may represent real equilibria.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 113
    Electronic Resource
    Electronic Resource
    Syntheses of 3-Heteroaryl-2H-Azaphosphirene Tungsten Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 575-578 
    Details
    ISSN: 1434-1948
    Keywords: Phosphorus heterocycles ; 2H-Azaphosphirene complexes ; Carbene complexes ; Tungsten ; Cyclizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of 3-heteroaryl-substituted 2H-azaphosphirene pentacarbonyltungsten complexes are reported. The products were characterized by multinuclear NMR spectroscopy (1H, 13C, 15N, 31P, 183W); the structure of the 3-N-methylpyrryl-substituted 2H-azaphosphirene complex was determined by single-crystal X-ray structure analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 114
    Electronic Resource
    Electronic Resource
    Synthesis and Structure of the First Carbyne Complex Functionalized Zwitterionic α-Carbenium Phosphinates [Tp′(CO)2M ≡ C-P(O)2-C(NR2)2] (M = Mo, W; R = Me, Et) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 579-582 
    Details
    ISSN: 1434-1948
    Keywords: Carbyne complexes ; Molybdenum complexes ; Oxidations ; Tungsten ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of the phosphaalkenyl-substituted carbyne complexes [Tp′(CO)2M≡C-P=C(NR2)2] (1a: M = Mo, R = Me; 1b: M = W, R = Me; 2a: M = Mo, R = Et; 2b: M = W, R = Et) with molecular dioxygen cleanly affords the orange carbyne complexes [Tp′(CO)2M≡C-P(O)2C(NR2)2] [3a: M = Mo, R = Me; 3b: M = W; R = Me; 4a: M = Mo, R = Et; 4b: M = W, R = Et; Tp′ = HB(3,5-Me2HC3N2)3], which are functionalized at the methylidyne carbon atom by an α-carbenium phosphinate moiety. The novel compounds have been characterized by IR, 1H-, 13C-, and 31P-NMR spectroscopy. In addition, the molecular structure of 4a has been determined by a single-crystal X-ray structure analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 115
    Electronic Resource
    Electronic Resource
    Cyclopentadienyl Complexes of Yttrium Aminotroponiminates: An Example for an Improved Alternative Ligand System (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 593-596 
    Details
    ISSN: 1434-1948
    Keywords: Yttrium ; Aminotroponiminate ; Cyclopentadienyl ; Dynamic NMR ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixed aminotroponiminate ([ATI]-) cyclopentadienyl complexes were prepared using two different synthetic routes. Reaction of [[(iPr)2ATI]YCl2(THF)2]2 (1) with KCp* (Cp* = C5Me5) or Li[C5H3(SiMe3)2] affords [(iPr)2ATI]YCp2* (2a) and [(iPr)2ATI]Y[C5H3(SiMe3)2]2 (2b), respectively. Moreover, [(iPr)2ATI]YCp2* has also been obtained from the reaction of Cp2*Y(μ-Cl)2Li(OEt2)2 (3) and [(iPr)2ATI]K. The single crystal X-ray structure of [(iPr)2ATI]YCp2* shows that the steric demand of the [(iPr)2ATI]- ligand is somewhat similar to that of the well-known cyclopentadienyl group and diazadiene ligand. [(iPr)2ATI]Y[C5H3(SiMe3)2]2 shows a dynamic behavior in solution (1H NMR), which is essentially caused by rotation of the cyclopentadienyl group rather than by migration of the [(iPr)2ATI]- ligand.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 116
    Electronic Resource
    Electronic Resource
    The Conformational Flexibility of Oxidized Cytochrome c Studied through Its Interaction with NH3 and at High Temperatures (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 583-591 
    Details
    ISSN: 1434-1948
    Keywords: Cytochrome c ; Hyperfine shift ; Magnetic susceptibility anisotropy ; NMR spectroscopy ; Heme proteins ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of ammonia to oxidized horse heart cytochrome c has been studied by 1H-NMR, EPR, and CD spectroscopy at pH = 8.0. The affinity constant of the ligand is in the range 1.5-4 M-1. The 1H-NMR spectra of the heme group have been found to be similar to those of the high-pH forms, high-temperature forms, and cyanide adduct of the Met80Ala mutant of S. cerevisiae iso-1-cytochrome c. The assignment of a number of signals has led to the determination of the values of the magnetic anisotropy and of the orientation of its axes. The latter are similar to those of the Met80Ala cyanide derivative. The assignment of the high-temperature species has been further pursued during this research. The analysis of the NMR data of the NH3 adduct leads to the conclusion that substitution of Met80 at high pH or high temperature occurs through a ligand with cylindrical symmetry. This supports the suggestion that Met80 is substituted by a lysine at high pH.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 117
    Electronic Resource
    Electronic Resource
    P-Alkylated (1S,2S)-Cyclopentane-1,2-diylbisphosphanes with Four Stereogenic Centers and Some Group 10 Metal(II) Complexes Containing the (1S,2S)-C5H8[P(CH3)C8H15-cyclo]2 Ligand (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 597-603 
    Details
    ISSN: 1434-1948
    Keywords: Chirality ; P ligands ; Nickel ; Palladium ; Platinum ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-initiated P-H addition of (1S,2S)-C5H8(PH2)2 to cycloalkenes gave bis(secondary phosphanes), (1S,2S)-C5H8[P(H)CnH2n-1-cyclo]2 (n = 5-8), as mixtures of RP,RP′, SP,SP′, and RP,SP′ diastereomers. The three diastereomers of the peralkylated chiral P2 ligand (1S,2S)-C5H8[P(CH3)C8H15-cyclo]2 and its complexes with NiCl2, PdI2, and PtI2 were prepared. The structures of [(1S,2S)-C5H8{P(CH3)C8H15-cyclo(R)}2NiCl2] · [(1S,2S)-C5H8{P(CH3)C8H15-cyclo-(S)}2NiCl2],(1S,2S)-C5H8{P(CH3)C8H15-cyclo-(R)}2PdI2, and (1S,2S)-C5H8{P(CH3)C8H15-cyclo-(R)}2PtI2 were determined by X-ray diffraction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 118
    Electronic Resource
    Electronic Resource
    C-C Coupling Reactions of (Sulfene)ruthenium Complexes with Enolates (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 605-611 
    Details
    ISSN: 1434-1948
    Keywords: Enolates ; Nucleophilic additions ; Ruthenium ; S ligands ; Sulfenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfene complexes [CpRu(PR′3)2(RHC=SO2)]PF6 (2a-d) are obtained from the corresponding sulfur dioxide complexes 1a-c and diazomethane or -ethane. Reaction of [CpRu(dppm)(SO2)]Cl (1d) and phenyldiazomethane gives the chlorobenzylsulfinato complex [CpRu(dppm)(SO2CHPhCl)] (3). Alternatively, 2a may be synthesized by sulfur dioxide addition to the carbene complex [CpRu(dppm)(CH2)]PF6 (5) which, in turn, is obtained from the corresponding methyl complex [CpRu(dppm)(CH3)] and [Ph3C]PF6. Treatment of 2a-d or 3 with the enolates of cyclic 2-methyl-1,3-diketones, methyl malonates, open-chain cyano or β-oxo esters, and cyclic β-oxo esters gives the C-C coupling products 6a, b, 7a-e, 8a-c, 9a-c in high yields and, in one case, with high diastereoselectivity as well. The functionalized sulfinate ligands thus formed may be alkylated and subsequently removed from the metal center by ligand substitution with acetonitrile. After MeCN/SO2 exchange, the ruthenium complex can be recycled.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 119
    Electronic Resource
    Electronic Resource
    Towards New Iron(III) Chelators: Synthesis and Complexing Ability of a Water-Soluble Tripodal Ligand Based on 2,2′-Dihydroxybiphenyl Subunits (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 613-619 
    Details
    ISSN: 1434-1948
    Keywords: Dihydroxybiphenyl ; Iron chelation ; Formation constants ; Protonation constants ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new water-soluble iron(III) sequestering agent has been designed. The tris-bidentate tripodal ligand consists of three 2,2′-dihydroxybiphenyl subunits connected via amide linkages at their meta (4-) positions to a framework of the “tren” type. The key step of the synthesis involves the coupling of suitably substituted monophenyl moieties in order to obtain the biphenyl precursor. The deprotonation constants of the ligand, and the formation and deprotonation constants of the FeIII complex have been determined from potentiometric and spectrophotometric measurements. The results are compared with those of a previously described homologous ligand in which the chelating subunits are attached to the tren framework via the ortho (3-) position of the biphenyl rather than the 4-position.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 120
    Electronic Resource
    Electronic Resource
    Syntheses and Structures of Molecular Diphenolatonickel Compounds Containing Trimethylphosphane Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 621-627 
    Details
    ISSN: 1434-1948
    Keywords: Nickel ; Oxidation ; Phenols ; Structure ; Dynamic NMR spectroscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of substituted phenols and dioxygen with Ni(PMe3)4 yields the low-spin tetracoordinate diphenolatonickel compounds Ni(OAr)2(PMe3)2 [ArOH = 2-tert-butylphenol (1), 2-tert-butyl-4-methylphenol (2), 2-tert-butyl-6-methylphenol (3), 2,4-di(tert-butyl)phenol (4), 2-tert-butyl-4-methoxophenol (5), 2-chloro-4-tert-butylphenol (6), 2-isopropylphenol (7), 3-tert-butylphenol (8)]. As is revealed by variable temperature 1H- and 13C-NMR spectroscopy the complexes constitute a mixture of two isomers, each of which can be observed separately at lower temperatures when interconversion is slower. An additional 6-carbaldehyde function transforms the phenolate into a chelating ligand, giving rise to a high-spin hexacoordinate compound Ni(OAr)2(PMe3)2 (9). X-ray crystal-structure determinations of 2 and 3 show a trans square-planar structure, and that of 9 shows a trans octahedral arrangement of donor atoms P2O4. Bulky substituents in the 3- or 4-position, or non-demanding substituents in the 2-position, are less effective in stabilizing molecular diphenolatonickel complexes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 121
    Electronic Resource
    Electronic Resource
    Replacement of One CO Unit in Dicarbonyl(η5-cyclopentadienyl)cobalt Derivatives by Bis(tert-butylsulfonyl)acetylene (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 629-632 
    Details
    ISSN: 1434-1948
    Keywords: Alkyne complexes ; Carbonyl complexes ; Cobalt ; CO replacement ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of dicarbonyl(η5-cyclopentadienyl)cobalt (1) and some of the Cp-ring substituted congeners with bis(tert-butylsulfonyl)acetylene (BTSA) results in the replacement of one CO group by the BTSA moiety. The variation of the yields and reaction times indicates a dependence of the reactivity of 1-6 with BTSA as a function of substituents. X-ray investigations of the products show that the alkyne unit is strongly bound to the metal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 122
    Electronic Resource
    Electronic Resource
    2,3,4-Tricarba-nido-hexaboranes(7) with a Bridging B-Ethyl-B Moiety (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 633-637 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Boron ; Carboranes ; NMR spectroscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydroboration of diethyl(1-propynyl)borane 1 with tetraethyldiborane(6) in the presence of a catalytic amount of trimethyl- or tributyltin chloride gave two new organo-substituted carboranes 6 and 7 with 2,3,5-tricarba-nido-hexaborane(7) and 2,3,4-tricarba-nido-hexaborane(7) skeletons, respectively, along with polymeric material and the known organo-substituted 1-carba-arachno-pentaborane(10) (3) and pentaethyl-1,5-dicarba-closo-pentaborane(5) (4). Selective 11B(5,6) decoupled 13C-NMR spectra indicate an unprecedented B(5)-ethyl-B(6) bridge in 7. This structure is supported by the agreement between experimental and calculated 11B- and 13C-chemical shifts on a model compound 7d with methyl groups in the 1,2,3,5,6-positions and an ethyl group bridging B(5) and B(6).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 123
    Electronic Resource
    Electronic Resource
    Aziridines as Complex Ligands: Coordination and Ring Opening (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 645-650 
    Details
    ISSN: 1434-1948
    Keywords: Aziridines ; Coordination ; Ring opening ; Metallacycle ; N-Chirality ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photolytically induced CO substitution reactions of CpMn(CO)3 with N-phenylaziridine and of W(CO)6 with 2,2-dimethylaziridine lead to the N-coordinated aziridine complexes Cp(CO)2Mn{N(Ph)CH2CH2} and (CO)5W{N(H)CH2CMe2}. Both are stable with respect to thermal alkene elimination. The thermal reaction of Cp(CO)3MoCl with N-hydroxyethylaziridine leads to the metallaheterocyclic compound Cp(CO)2MoNH(CH2CH2OH)CH2CH2C(O). It might be formed by several reaction steps including a Cl migration with nucleophilic ring opening, a CO insertion reaction forming the β-aminoacyl ligand and finally a hydrolytic process. The X-ray structure analysis of Cp(CO)2Mn{N(Ph)CH2CH2} and (CO)5W{N(H)CH2CMe2} shows three-membered-ring ligands N-bonded to the metal atoms with a trigonal pyramidal configuration at the nitrogen atoms. The X-ray structure analysis of Cp(CO)2MoNH(CH2CH2OH)CH2CH2C(O) reveals a five-membered heterocyclic ring system, including the molybdenum atom, a carbonyl function and an ammonium center.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 124
    Electronic Resource
    Electronic Resource
    A TXRF and Micro-Raman Spectrometric Reconstruction of Palettes for Distinguishing Between Scriptoria of Related Medieval Manuscripts (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 639-644 
    Details
    ISSN: 1434-1948
    Keywords: Manuscripts ; Scriptoria ; TXRF ; Micro-Raman spectroscopy ; Pigments ; Middle ages ; Azurite ; Gold initials ; Workshops ; Renaissance ; Mercatellis ; Codicology ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Assigning related medieval manuscripts to different workshops on the basis of codicological characteristics, is not straightforward. We present the first attempt to distinguish between scriptoria by means of a large-scale total reflection X-ray fluorescence (TXRF) analysis of pigment elements and an identification of pigment molecules with micro-Raman spectroscopy. We analyzed 324 colored items in 10 medieval manuscripts, of which 7 are folio-sized illuminated manuscripts, all ordered by Raphael de Mercatellis in the late 15th and early 16th century. Palettes in miniatures were not yet examined. Blue palettes are exclusively azurite-based and are easily differentiated by means of the respective amounts of Ti, Ba, and As. Differences for green palettes are also pronounced. The green Cu-based pigment was not yet identified, but it certainly is not malachite or verdigris. Red pigments used are HgS, vermilion, and Pb3O4, red lead. The Flemish gold-leaf technique is used. The 7 Mercatellis manuscripts show two different palettes, both different from the non-Mercatellis manuscripts. The grouping of the Mercatellis manuscripts according to date and to palettes is, in general, consistent with a grouping on the basis of a classical codicological analysis, although some conflicting results are obtained. A quantitative and qualitative reconstruction of palettes by means of TXRF- and Raman-spectra, provides with a complimentary and objective tool for distinguishing between scriptoria.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 125
    Electronic Resource
    Electronic Resource
    Reactions and Coordination Properties of the First Secondary Carbaboranyldiphosphane: 1,2-Bis(phenylphosphanyl)-1,2-dicarba-closo-dodecaborane(12) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 651-656 
    Details
    ISSN: 1434-1948
    Keywords: Secondary carbaboranyldiphosphane ; Transition-metal complexes ; Crystal structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When a mixture of stereoisomers of rac- and meso-1,2-bis(phenylphosphanyl)-1,2-dicarba-closo-dodecaborane(12) (1a, b; 1a/1b = 3:1) is treated with [Cp2ZrMe2] in boiling toluene for 2 h, the formation of three phosphorus-containing products, namely meso-[Cp2Zr(PPh)3] (3), (PPh)4 (4) and (PPh)5 (5), ratio 2.8:1.1:1.0, was observed by 31P-NMR spectroscopy. In the 11B-NMR spectrum of the reaction mixture, only signals for 1,2-dicarba-closo-dodecaborane(12) were observed. When zirconocene, prepared in situ from [Cp2ZrCl2] and BuLi, was treated with 1a, b at low temperature and then heated to reflux in toluene for 2 h, only formation of 3 and 1,2-dicarba-closo-dodecaborane(12) was observed. The mixture of stereoisomers of 1a, b reacts with CuCl in THF to give rac- and meso-[CuCl(THF){1,2-(PHPh)2C2B10H10}] (7a, b), which is only stable in THF solution and loses THF in vacuo over several hours to yield the insoluble colorless complex [CuCl{1,2-(PHPh)2C2B10H10}]n (8). In THF solution, 7 reacts with PPh3 to give the stable isolable complex [CuCl(PPh3){1,2-(PHPh)2C2B10H10}] (9). No reaction of 1a, b is observed with [Cp′Mo(CO)3]2 (Cp′ = C5H4Me) in boiling THF, while only decomposition occurs in boiling toluene. However, [(NBD)Mo(CO)4] (NBD = norbornadiene) reacts smoothly with 1a in toluene at room temperature to give cis-rac-[Mo(CO)4{1,2-(PHPh)2C2B10H10}] (10). Compounds 7, 9, and 10 were characterized spectroscopically (1H, 31P, 11B, 13C NMR, IR), and an X-ray structure determination was carried out on 10.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 126
    Electronic Resource
    Electronic Resource
    Controlled Degradation of a Ligand-Deficient Complex: From [{Cd(C6F5)(STrt)}4] to [{Cd(C6F5)(STrt)}3(OH)]- and [Cd(C6F5)(STrt)2]- (Trt = Triphenylmethyl) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 657-662 
    Details
    ISSN: 1434-1948
    Keywords: Cadmium ; Crown compounds ; Pentafluorophenyl ; Potassium ; S ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(pentafluorophenyl)cadmium, [Cd(C6F5)2], reacts with equimolar amounts of triphenylmethanethiol, TrtSH, in toluene to give [{Cd(C6F5)(STrt)}4] · 1.5 tol (1). The cuboidal complex of 1 has been transformed into the heterometallic cuboidal complex [{Cd(C6F5)(STrt)}3(OH)K(THF)3] (2) by reaction with KOH in tetrahydrofuran. In the presence of 18-crown-6, the compound [K(18-crown-6)(THF)2][{Cd(C6F5)- (STrt)}3(OH)] · THF (3) has been obtained instead of 2. X-ray structure analysis shows the anion of 3 to be an incomplete cuboidal complex, which alternatively can be described as a cyclic trimer of the {Cd(C6F5)(STrt)} unit stabilized by a μ3-hydroxo ligand. The compound [K(18-crown-6)(THF)2][Cd(C6F5)(STrt)2] (4) has been isolated from reaction mixtures containing 1, KSTrt and 18-crown-6. The cadmium atom in 4 is three-coordinated, in contrast to the cadmium atoms in 1-3, which are situated in strongly distorted coordination tetrahedra. Intramolecular C6H5···C6F5···C6H5 stacks in 4 are interpreted as resulting from attractive ligand-ligand interactions. Spectroscopic data, particularly from 13C-NMR and IR spectra, are consistent with the order of ligand deficiency: 1 〉 2 〉 3 〉 4. The macrocyclic, eight-coordinate complex [K(18-crown-6)(THF)2]+ in 3 and 4 contains trans arranged THF ligands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 127
    Electronic Resource
    Electronic Resource
    Aminoethyl-Functionalized Cyclopentadienyl Complexes of d-Block Elements (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 663-674 
    Details
    ISSN: 1434-1948
    Keywords: Aminoethyl-functionalized cyclopentadienyl complexes ; d-Block elements ; Hemilabile N-ligands ; Intramolecular coordination ; Tethered aminoethyl groups ; Water-soluble organometallics ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The introduction of an aminoethyl side chain into cyclopentadienyl compounds of many d-block elements leads to interesting changes in structure and reactivity compared to the parent species: (i) A hemilabile bonding situation is observed in complexes with low-valent transition-metal centers; (ii) amino-group coordination to an adjacent metal or nonmetal center creates novel types of bimetallic compounds; (iii) complexes with a tethered ammoniumethyl group often show good solubility in protic solvents, relevant with regard to organometallic chemistry in water. These features together with others are described in this review, which informs about the synthesis and properties of this new type of transition-metal complexes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 128
    Electronic Resource
    Electronic Resource
    Pyrazole as a Donor Function in Neopentane-Based Tripod Ligands RCH2C(CH2pyrazol-1-yl)3-n(CH2PR2)n - Synthesis and Coordination Chemistry (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 675-692 
    Details
    ISSN: 1434-1948
    Keywords: Tripodal ligands ; Pyrazolyl donors ; Molybdenum ; Hydrogen bonds ; 2D-NMR ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chlorine functions of CH3C(CH2Cl)3, 1, may be replaced by pyrazolyl (pz) as well as imidazolyl (im) residues under the conditions of nucleophilic substitution leading to tripodal ligands CH3C(CH2X)3, X = pz, 2; X = im, 3. As a means of introducing two nitrogen donors and one phosphorus donor into a tripod ligand, substitution of the Br and OMs functions in O(CH2)2C(CH2Br)(CH2OMs), 8, by nitrogen nucleophiles and subsequent cleavage of the oxetane ring by a phosphide nucleophile to give HOCH2C(CH2PPh2)(CH2X)2 has been developed, furnishing 10a (X = pz) and 10d (X = NEt2), respectively. For the synthesis of 10a, K-pz was used as the nucleophile, while 10d was prepared using azide in the initial step, which then had to be transformed into NEt2 in two subsequent steps. The nucleophugic functions of the oxetane 8 undergo selective substitution by K-pz and KPPh2 in THF to produce O(CH2)2C(CH2PPh2)(CH2pz), 9b. Phosphide cleavage of the oxetane function leads to HOCH2C(CH2PPh2)(CH2PR2)(CH2pz), R = Ph, 10b; R = 3,5-Me2(C6H3), 10c. - The tris(pyrazolyl) tripod ligand 2 reacts with (MeCN)3Mo(CO)3to give 2 · Mo(CO)3(MeCN), 12a, in which only two of the three donor functions are coordinated. Upon reaction with 10a, the same reagent gives 10a · Mo(CO)4, 12b, with one pyrazolyl coordinated and the other involved in intramolecular hydrogen bonding to the CH2OH function (N···H-O distance 280 pm). Blocking of the OH function of 10a by etherification, i.e. to form EtOCH2C(CH2PPh2)(CH2pz)2, 11, does not dramatically affect the coordination capabilities with 11 · Mo(CO)3(MeCN), 12d, being formed upon treatment with (MeCN)3Mo(CO)3. Again only one pz function is coordinated to the metal. Bidentate coordination by two phosphorus donors of 10c is observed in 10c · Mo(CO)3(MeCN), 12d. The dangling arm pz donor function and the CH2OH group are intermolecularly hydrogen-bonded in this case. When the bulky P[3,5-Me2(C6H3)]2 substituent of 10c is replaced by the less sterically demanding PPh2 donor in 10b, η3-coordination is finally observed with the formation of 10b · Mo(CO)3, 13. The coordination capabilities of the new ligands are rationalized in terms of the size (six-, seven-, and eight-membered rings) and interference of the chelate cycles. All compounds have been characterized by the usual analytical and spectroscopic methods, with a complete assignment of the NMR data achieved by a combination of 2D-NMR techniques in some cases. The structures of the coordination compounds have additionally been deduced by X-ray methods.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 129
    Electronic Resource
    Electronic Resource
    How to Derive Force Field Parameters by Genetic Algorithms: Modelling tripod-Mo(CO)3 Compounds as an Example (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 693-702 
    Details
    ISSN: 1434-1948
    Keywords: Genetic Algorithms ; Force field calculations ; Refinement of force field parameters ; Tripod metal compounds ; Conformational analysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Force field parameters used to describe the conformation of coordination compounds involving transition metals are generally derived by a trial-and-error procedure, until a somehow satisfying agreement between the calculated and observed conformations of a few members of a class of related compounds is reached. It is shown in this paper that a more general and less biased alternative is available, applicable to many structures at a time. Genetic Algorithms will effectively optimize force field parameters in an automatic way, on the basis of a potentially exhaustive set of all the structural data available for a given class of compounds. The feasibility of this procedure has been demonstrated by the derivation of force field parameters describing the conformational behaviour of tripod-Mo(CO)3 compounds [tripod= RCH2C(CH2X)(CH2Y)(CH2Z), X,Y,Z = PR′R′′)] by simultaneous optimization based on the structure of ten individual molecules. With the force field parameters relevant to the organic part of these compounds taken from MM2*, the parameters involving contributions from the Mo center were refined. The agreement between observed and calculated structures is characterized by an rms deviation of around 0.3 Å for the ten structures contained in the data base. To assess the validity of this approach, the conformational space of CH3C(CH2PPh2)3Mo(CO)3 was explored exhaustively. A contour diagram representing the relative energy of the molecule with respect to the rotational positions of its phenyl groups was found to effectively reproduce the scatter of these conformational parameters as earlier derived from an analysis of 82 relevant compounds. - As a further assessment, the conformational space of CH3C[CH2P(o-Tol)2]3Mo(CO)3, which was not included in the data base, has been analyzed. It is found that the structure corresponding to the global energy minimum corresponds to that observed in the crystal with an rms deviation of only 0.3 Å. The novel approach to problems of this type - Genetic Algorithms had not previously been applied in this context - thus appears promising.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 130
    Electronic Resource
    Electronic Resource
    Four-Coordinate Group-14 Elements in the Formal Oxidation State of Zero - Syntheses, Structures, and Dynamics of [{(CO)5Cr}2Sn(L2)] and Related Species (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 703-720 
    Details
    ISSN: 1434-1948
    Keywords: Germanium ; Tin ; Lead ; 119Sn NMR ; Dynamic NMR ; Salt metathesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sodium salts Na2[{(CO)5M}2EX2] (M = Cr, Mo, W; E = Ge, Sn, Pb; X = Cl, I, OOCCH3) react with 2,2′-bipyridine (bipy) to form neutral compounds [{(CO)5M}2E(bipy)] (E = Sn: 1a-1c; E = Ge: 3a; E = Pb: 4). 1,10-Phenanthroline (phen) analogues of compounds 1a-1c and 3a [{(CO)5M}2E(phen)] (E = Sn: 1d-1f, E = Ge: 3b) are as well accessible. The 2,2′-bipyridine ligand in 1 may be formally replaced by two pyridine (py) ligands resulting in [{(CO)5M}2Sn(py)2] (1g: M = Cr, 1h: M = W). The bis-bidentate ligand 2,2′-bipyrimidine (bpmd) is found to coordinate just one [{(CO)5M}2Sn] entity in [{(CO)5M}2Sn(bpmd)] (2b: M = Cr, 2c: M = W). The biimidazolato (biim) ligand binds two [{(CO)5Cr}2Sn] moieties in [{(CO)5Cr}2Sn(biim)Sn{Cr(CO)5}2]2-, 2a. It is shown by 1H-NMR that the pyrimidine entities in these compounds (2b, 2c) are able to rotate by a full 180° turn-around with respect to one another. This process must involve complete de-coordination of at least one of the two nitrogen donors in again at least one of the chelate cycles, the activation energy for this process being around 60 kJ/mol. By 119Sn-NMR spectroscopy of almost all of the tin compounds described it is shown that equilibria between [{(CO)5M}2Sn(L2)] and [{(CO)5M}2Sn(L)] + L exist in all cases. From the temperature dependence of the δ values it is concluded that the activation barriers for this association/dissociation process is below 10 kJ/mol. The structures of all new compounds are documented by X-ray analyses and all compounds are characterized by the usual analytical and spectroscopical techniques.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 131
    Electronic Resource
    Electronic Resource
    Synthesis, Structure, Electronic, Redox, and Magnetic Properties of a New Mixed-Valent Mn-Oxo Cluster: [Mn2III,IVO2(N,Nbispicen)2]3+ (N,Nbispicen = N,N-bis(2-pyridylmethyl)-1,2-diaminoethane) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 721-727 
    Details
    ISSN: 1434-1948
    Keywords: Manganese ; EPR spectroscopy ; Spectroelectrochemistry ; Mixed-valent compounds ; Tripodal ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and structural characterization of the novel [MnIII,IV2O2(N,Nbispicen)2](ClO4)3·CH3CN complex employing the tetradentate ligand N,Nbispicen = N,N-bis(2-pyridylmethyl)-1,2-diaminoethane are reported. Magnetic properties were determined and show that the ground state is a spin doublet. This can be quantitatively interpreted by antiferromagnetic coupling between a Mn(III) high spin and a Mn(IV) (J = -316 cm-1). The 16 line solution EPR spectrum exhibits an unusual splitting in the low field resonances. The following rhombic tensors were needed to simulate the EPR spectrum: |A1x|= 160 10-4 cm-1, |A1y| = 144 10-4 cm-1, |A1z|= 109 10-4 cm-1, |A2x|= 69 10-4 cm-1, |A2y| = 72 10-4 cm-1, |A2z| = 75 10-4 cm-1, gx = 2.001, gy = 1.996, gz = 1.984. The classical ligand field theory of local [gIII] and [gIV] tensors implemented with the first order perturbation theory to describe the properties of the pair does not result in a satisfying description of the [g1/2] tensor unless a large reduction in the spin-orbit constant is invoked. A simplified version of second-order perturbation theory leads to effects in qualitative agreement with experiment but weak as expected from the large |J| value. The magnitude of these effects depends, however, on the anisotropy effects on each Mn ion. It is suggested that determination of the anisotropy of the magnetic properties of the monomeric Mn(III) and Mn(IV) moieties would be a valuable goal for a future study of these mixed valent dimanganese-di-μ-oxo complexes. The complex exhibits two quasi-reversible waves in the cyclic voltammogram, one at E1/2 = 0.18 V vs SCE for the III/IV █ III/III couple and the other at E1/2 = 0.98 V vs SCE for the III/IV █ IV/IV couple. The UV-Vis spectra of the three redox states have been recorded spectroelectrochemically.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 132
    Electronic Resource
    Electronic Resource
    Catalytic Formation of Oligopeptides from α-Amino Acid Esters with (p-Cymene)ruthenium(II) Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 729-731 
    Details
    ISSN: 1434-1948
    Keywords: Catalysis ; Oligomerization ; Organometallics ; Oligopeptides ; Ruthenium complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Consecutive addition of one-equivalent portions of glycine ethyl ester to [(p-cymene)Ru(GGGOMe-H+)Cl] leads to considerable amounts of (tetra- to nonapeptide)ruthenium complexes in a one-pot reaction, in which the (p-cymene)RuCl fragment acts as a catalyst. The analogous reaction with alanine methyl ester affords AGGG and AAGGG complexes as the main products. The course of these metal-catalyzed peptide oligomerizations has been followed by mass spectrometry. The synthesis and characterization of the pentapeptide complex [(C6Me6)Ru(GGGGGOMe-H+)] is reported.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 133
    Electronic Resource
    Electronic Resource
    Synthesis and Structure of Gallium/Silicon Heterocycles with a Ga2Si2 and a Ga3Si Framework⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 745-749 
    Details
    ISSN: 1434-1948
    Keywords: Gallium ; Silicon ; Heterocycles ; Main group elements ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of Ga2X4· 2 dioxane with four equivalents of (Me3Si)3SiLi(thf)3 (= hypersilyllithium) affords for X = Br a 1,3,2,4-disiladigalletane together with tetrahedral hypersilylgallium(I). For X = Cl an anionic 1,2,3,4-silatrigalletanate, a four-membered heterocycle with a Ga3 unit, is isolated. These primary examples of gallium/group-14 heterocycles have been investigated by NMR spectroscopy as well as by X-ray single-crystal structure analysis. In addition, the synthesis and structure of bis(hypersilyl)gallium chloride is described. This monomeric molecule has a nearly T-shaped Si2GaCl framework.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 134
    Electronic Resource
    Electronic Resource
    The π-Electron-Accepting Ability of the Boron Atom in Ethynylboranes and Related Compounds - An Approximate Weight Computation for Resonance Structures⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 733-744 
    Details
    ISSN: 1434-1948
    Keywords: Aminoboranes ; Ab initio calculations ; Valence-bond theory ; Resonance structures ; Alkynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theoretical analysis was performed to quantify the π-electron-accepting ability of the boron atom in ethynylboranes. An expansion technique was employed which permits to obtain a set of localized bonding schemes and their weights from a delocalized molecular orbital determinantal wavefunction. The derived manifold of bonding schemes is close to the classical resonance hybrid used in organic chemistry (valence-bond description). We quantified the π-electron transfer into the empty π-orbital of the boron atom by investigating nine model compounds where substituents with π-electron-donating ability are adjacent to a boron atom. This led to an ordering of the substituents according to their electron-donating ability towards boron. The boron atom hesitates to accept π-electrons from the ethynyl group in ethynylboranes in particular when good π-donors like amino groups are present. The π-electron donation from the vinyl group to the adjacent boron centre is slightly stronger than from the ethynyl group. Nitrogen lone-pair electrons are easily transferred to a neighbouring boron centre. Bonding schemes and their weights are in line with computed bond lengths and rotational barriers. Moreover, our theoretical results rationalize previous NMR and X-ray experiments and are in line with the reactivity of related compounds. It is demonstrated that bond lengths alone do not necessarily correlate with the degree of π-bonding and should be discussed with caution. The analysis is substantiated by showing that weights for covalent bonding schemes, as obtained from the simple restricted closed-shell MO determinant, correlate with bond strengths. Furthermore, a correlation of bonding-scheme weights with quantities based on the fragment orbital approach is presented. This novel correlation elucidates molecular properties which determine the extent of the π-electron transfer to the boron atom and permits a quantitative interpretation and prediction of intramolecular π-bonding.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 135
    Electronic Resource
    Electronic Resource
    Aspects of the Chemistry of the Cyclic Phosphonium Salt [Ph2PaP(Cl)N(SiMe3)C(tBu)=CbH(Pa-Cb)]Cl and the Related Diazadiphosphetidine [ClPaN(R)P(Cl)NbR(Pa-Nb)] [R = C(tBu)=C(H)SiMe3] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 751-760 
    Details
    ISSN: 1434-1948
    Keywords: Phosphorus chemistry ; Phosphonium salts ; Diazadiphosphetidines ; Phosphazoles ; 1-Azaallyl compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report the preparation of the novel phosphonium salts [Ph2PaP(NR′2)N(R)C(tBu)=CbH]A(Pa-Cb) (2a; R′ = Et, R = SiMe3, A = Cl; 2b: R′ = Me, R = SiMe3, A = Cl; 2c: R = Et, R′ = SiMe3, A = [OSO2CF3]; 2d: R′ = Et, R = SiMe3, A = [BPh4]; 4: R′ = Et, R = H, A = Cl) and trans-1,3,2,4-diazadiphosphetidines R′2NPaN(R)P(NR′2)Nc(R)(Pa-Nc) [3a: R′ = Et, R = C(tBu)=C(H)PPh2; 3b: R′ = Me, R = C(tBu)=C(H)PPh2; 7: R′ = Me, R = C(tBu)=C(H)SiMe3]. Reaction of 3a with Cu2I2 led to the P- and P,P′-centred complexes [Cu(I)(3a)] (5a) and [{Cu(I)}2(3b)] (5b) [R = C(tBu)=C(H)PPh2]. The phosphazole NaC(tBu)C(H)CcPaN(Me)(CH2)2NcMe(Na-Pa)(Cc-Nc) (8) was obtained by a remarkable hetero-cycloaddition reaction from the diazadiphosphetidine ClPaN(R)P(Cl)NbR(Pa-Nb) [6: R = C(tBu)=C(H)SiMe3] and the electron-rich olefin [=CaN(Me)(CH2)2NaMe(Ca-Na)]2 and was oxidised with S8 yielding NaC(tBu)C(H)CcPa-(S)N(Me)(CH2)2NcMe(Na-Pa)(Cc-Nc) (9). Compounds 2-9 were characterised by multinuclear NMR spectroscopy, mass spectrometry for 5-9, while single-crystal X-ray diffraction data are provided for 3a and 5a.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 136
    Electronic Resource
    Electronic Resource
    Novel Organoborane Lewis Acids via Selective Boron-Tin Exchange Processes Steric Constraints to Electrophilic Initiation by the Boron Halide (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 761-769 
    Details
    ISSN: 1434-1948
    Keywords: Organometallics ; Boron ; Lithium ; Tin ; Metal-metal exchange ; Electrophilic reagents ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the purpose of preparing novel mono- and bidentate organoboron Lewis acids, the scope and limitations of synthesizing the requisite organoboranes by the boron-tin exchange between a boron halide and the appropriate organostannane have been examined in detail. The following organotin derivatives have been obtained either from the corresponding RMgBr or RLi reagent and MenSnCl4-n or from a Barbier procedure using the organic halide, Me3SnCl and magnesium metal: 1,2-bis(trimethylstannyl)ethyne, o-, m-, and p-bis(trimethyl-stannyl)benzenes, α,o-bis(trimethylstannyl)toluene, α,α-bis(trimethylstannyl)-o-xylene, and 2,2-dimethyl-2-stannaindane. The individual interaction of the 1,2-bis(trimethylstannyl)ethyne and the isomeric bis(trimethylstannyl)benzenes with Et2BBr produced the corresponding bis(diethylboryl)-derivatives. By contrast, with Et2BCl the α,o-bis(trimethylstannyl)toluene gave only o-diethylboryl-α-trimethylstannyltoluene and with BCl3 the α,α′-bis(trimethylstannyl)-o-xylene formed only,-bis-(chlorodimethylstannyl)-o-xylene. Furthermore, in the attempted double boron-tin exchange between o-bis(trimethylstannyl)benzene and BCl3, an unprecedented rearrangement of the 1-(dichloroboryl)-2-(trimethylstan-nyl)benzene intermediate into its 1-[chloro(methyl)boryl]-2-(chlorodimethylstannyl) isomer was observed. Likewise, o-bis(trimethylstannyl)benzene with PhBCl2 produced by a similar rearrangement 1-[methyl(phenyl)boryl]-2-(chloro-dimethylstannyl)benzene. The thermolysis of such boranes led variously to definite dimers or ill-defined oligomers. Preliminary studies of the properties of these organoboranes have identified the heightened Lewis acidity of 1,2-bis(diethylboryl)ethyne and the π-electron delocalization involving the 2pz-boron orbitals in the 9,10-dihydro-9,10-diboraanthracene system. Finally, an electronic mechanism for the boron-tin exchange has been developed to account for the selectivity of the boron halide's attack at unsaturated carbon-tin bonds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 137
    Electronic Resource
    Electronic Resource
    Novel Chiral Oxazoline Ligands for Potential Charge-Transfer Effects in the Rh(I)-Catalysed Enantioselective Hydrosilylation (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 771-781 
    Details
    ISSN: 1434-1948
    Keywords: Oxazolines ; Charge-transfer ; 4,4′-Bipyridine ; Enantioselective hydrosilylation ; Rh(I)-complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel 2-(4,4′-bipyridin-2-yl)oxazolines, bearing a chiral oxazoline moiety, were synthesised starting from 4,4′-bipyridine and selectively monomethylated in the N′-position. After coordination to rhodium these electron-poor ligands are supposed to exhibit charge-transfer effects with electron-donating substrates in the Rh(I)-catalysed enantioselective hydrosilylation (see next publication). Similar effects were expected from 4,4′-bipyridine- and pyrazine-bisoxazolines after complexation with rhodium. For comparison 2-(4-phenylpyridin-2-yl)oxazoline ligands were synthesised. Rh(I)-complexes of selected ligands were prepared and characterised, including an X-ray structure analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 138
    Electronic Resource
    Electronic Resource
    Rh(I)-Catalysed Asymmetric Hydrosilylation using New Oxazoline Ligands with Potential Charge-transfer Properties (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 783-788 
    Details
    ISSN: 1434-1948
    Keywords: Enantioselective hydrosilylation ; Oxazoline ligands ; Charge-transfer ; 4,4-Bipyridine derivatives ; 2,5-Dimethoxyacetophenone ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel N′-methylated 2-(oxazolin-2-yl)-4,4′-bipyridinium salts, bearing a chiral oxazoline moiety, were tested in the Rh(I)-catalysed enantioselective hydrosilylation. After coordination to rhodium these electron-attracting ligands are supposed to exhibit charge-transfer effects with electron-donating substrates. Therefore, a new catalytic hydrosilylation reaction with 2,5-dimethoxyacetophenone as an electron-rich substrate was developed. The results were compared with those of the non-methylated 2-(oxazolin-2-yl)-4,4′-bipyridine and related ligands. In addition, the new ligands and Rh(I)-complexes were tested in the hydrosilylation of acetophenone.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 139
    Electronic Resource
    Electronic Resource
    Synthesis of Oxorhenium(V) Complexes Derived from 7α-Functionalized Testosterone: First Rhenium-Containing Testosterone Derivatives (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 789-793 
    Details
    ISSN: 1434-1948
    Keywords: Steroids ; Rhenium ; 7α-Substituted testosterone ; Androgen receptor ; Chelates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In an effort to assist in the preparation of metal-containing ligands for the androgen receptor, we have synthesized the first oxorhenium(V) complexes containing a pendant testosterone moiety. The key step in the synthesis involves the copper-catalysed, α-selective 1,6-Michael addition of a 4-pentenylmagnesium bromide to 6-dehydrotestosterone 17β-acetate. The α-stereoselectivity is governed by the presence of the C-19 methyl group. The absolute configurations of the epimers were investigated by 1H-NMR studies. Further chemical transformations of the 7α-pentenyl spacer introduced the terminal thiol group, needed for complex formation. The complex formation was accomplished by the “3+1” mixed-ligand concept using two different rhenium precursors. The obtained complexes differ with respect to the central donor atom of the tridentate ligand part, namely, S and O.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 140
    Electronic Resource
    Electronic Resource
    Crystal Structure and Formation of the Aluminium Hydroxide Chloride [Al13(OH)24(H2O)24]Cl15 · 13 H2O (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 795-797 
    Details
    ISSN: 1434-1948
    Keywords: Aluminium hydroxide chloride ; Crystal structure ; Tridecameric cation ; Structure of cation ; Formation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A basic aluminium chloride with high chlorine content (basicity 1.85) has been crystallized from a concentrated aqueous solution. Its crystal structure has been determined by X-ray structure analysis. The structure contains tridecameric cations of a novel type consisting only of interconnected AlO6 octahedra. The formation of these polycations is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 141
    Electronic Resource
    Electronic Resource
    Three-Dimensional Assemblies of Gold Colloids in Nanoporous Alumina Membranesast; (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 807-812 
    Details
    ISSN: 1434-1948
    Keywords: Gold colloids ; Self-assembly ; Nanoporous alumina ; Three-dimensional organization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Examples of a new class of three-dimensionally arranged gold colloids have been prepared in the nanoscale pores of alumina membranes. Immobilization of the colloid particles was achieved by a modification of the inner walls with alkoxysilanes Y-(CH2)x-Si(OR)3 and Y-(CH2)x-SiR(OR)2 bearing suitable functional groups (Y = NH2, SH), followed by anchoring of the colloids by self-assembly onto the modified surface. This procedure gives tight and stable ensembles of colloids on the walls. TEM analyses revealed uniform and random colloidal dispersions on the walls in the form of sub-monolayers without any aggregation. UV/Vis spectra of the filled membranes showed an absorption maximum at ca. 525 nm arising from an excitation of the plasmon resonance of the gold colloids. The dimensions of the pores can be “tuned” and given the diverse range of different colloids available, routes to novel catalysts and sensors can be envisaged.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 142
    Electronic Resource
    Electronic Resource
    Oxovanadium(IV) and -(V) Complexes with Aminoalcohol Ligands: Synthesis, Structure, Electrochemical, and Magnetic Properties (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 799-805 
    Details
    ISSN: 1434-1948
    Keywords: Aminoalcohol ligands ; Hydrogen bonds ; Magnetic properties ; Oxo complexes ; Vanadium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aminoalcohol ligands diethanolamine (H2dea) and triethanolamine (H3tea) react with [VO(acac)2] to yield the tetranuclear oxovanadium(IV) complexes [{VO(dea)}2{VO(acac)}2(μ2-OMe)2] (1) and [{VO(Htea)}2{VO(acac)}2(μ2-OMe)2] (2). In the case of the potentially bridging aminoalcohol ligands N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine (H4edte) and N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine (H4edtp) the corresponding oxovanadium(IV) complexes could not be isolated. Instead after air oxidation the ligand supported binuclear oxovanadium(V) complexes [{VO(acac)}2(edte)] (3) and [{VO(acac)}2(edtp)] (4) are obtained. The reaction of the ligand H4edtp with ammonium meta-vanadate in methanol solution leads to the methoxy bridged binuclear oxovanadium(V) complex [(VO)2(edtp)(μ2-OMe)2] (5). The tetranuclear oxovanadium(IV) complexes can be isolated as crystalline compounds 1 · 2 MeOH and 2 · 2 MeOH and have been characterized by IR, UV/Vis, and ESR spectroscopy as well as cyclic voltammetry and magnetic susceptibility measurements. Single-crystal diffraction studies reveal that the complexes 1 and 2 contain a tetranuclear {(VO)4(μ3-OR)2(μ2-OR)4}2+ core composed of three different types of edge-shared binuclear units, whereas the oxovanadium(V) complexes 3, 4, and 5 posses binuclear structures, that are either ligand supported as in the case of 3 and 4 or contain a μ2-methoxy bridged{(VO)2(μ2-OR)2}4+ core as in the case of 5. ESR and magnetic data indicate a singlet ground state for 1 · 2 MeOH and 2 · 2 MeOH, although competing ferromagnetic exchange interactions are operative within the tetranuclear core structure. In the solid state compounds 1 · 2 MeOH and 2 · 2 MeOH hydrogen bridged supramolecular structures are found. The hydrogen bonding scheme of both compounds leads to the formation of a similar chain arrangement of the tetranuclear complexes 1 and 2.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 143
    Electronic Resource
    Electronic Resource
    Silsesquioxanes as Ligands for Gold Clusters (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 813-817 
    Details
    ISSN: 1434-1948
    Keywords: Silsesquioxanes ; Gold clusters ; Self assembly ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new type of gold cluster has been synthesized using the silsesquioxane derivative (cyclopentyl)7Si8O12(CH2)3SH (T8-OSS-SH) to exchange the PPh3 ligands in (PPh3)12Au55Cl6 by T8-OSS-SH quantitatively. This exchange causes several important changes in the physical and chemical behavior of the compound. Owing to the presence of cyclopentyl substituents, the cluster becomes soluble in non-polar solvents such as pentane. The stability of this compound compared with that of the PPh3-protected cluster is considerably higher meaning that decomposition in solution, and even under the high-energetic irradiation in the microscope, is not observed over longer periods of time. The increase in the total diameter from 2.1 to ca. 4.4 nm is probably responsible for these advantageous properties, supported by strong S-Au bonds. The increase in size is also expressed as an increase in the activation energy for electron-tunneling processes through the ligand shells of neighboring clusters in a densely packed pellet. This increase is from 0.16 eV for (PPh3)12Au55Cl6 to 0.26 eV for the T8-OSS-SH-protected cluster.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 144
    Electronic Resource
    Electronic Resource
    Zinc Complexes of Tripodal N3O Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 827-832 
    Details
    ISSN: 1434-1948
    Keywords: Zinc complexes ; Tripodal ligands ; Ligand bridging ; Halide, phenolate, thiophenolate, and phosphate coligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tripodal N,O ligands bis(2-pyridylmethyl)(o-hydroxybenzyl)amine (L1) and bis(2-pyridylmethyl)(2-carboxyethyl)amine (L2) were tested for their ligating properties towards zinc. Zinc halides yielded L1·Zn-Hal (1a-c, Hal = Cl, Br, I) and L2·Zn-Hal (2a-c, Hal = Cl, Br, I). Subsequent treatment of L1 with ZnEt2 or Zn[N(SiMe3)2]2 and phenol, thiophenols or diphenylphosphate led to L1·Zn-OPh (3), L1·Zn-SAr (4) and L1·Zn-OPO(OPh)2 (5). Zinc salts of noncoordinating anions yielded oligonuclear ligand-bridged complexes [L1·Zn]ClO4 (6), [L2·Zn]ClO4 (7) and [L2·Zn]NO3 (8), of which 6 was identified as a phenolate bridged dimer and 8 as a η1-η2-carboxylate bridged polymer.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 145
    Electronic Resource
    Electronic Resource
    Synthesis, Structure, and Properties of Osmium Complexes Containing [Os(′S4′)] and [Os(′S2′)2] Fragments (′S4′2- = 1,2-Bis(2-mercaptophenylthio)ethane(2-), ′S2′2- = 1,2-Benzenedithiolate) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 819-826 
    Details
    ISSN: 1434-1948
    Keywords: S ligands ; P ligands ; Osmium ; Solvent effects ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In search for osmium complexes with sulfur-dominated coordination spheres that potentially bind and activate or stabilize nitrogenase relevant small molecules, several osmium-sulfur complexes containing 1,2-bis(2-mercaptophenylthio)ethane(2-) (′S4′2-) and benzenedithiolate (′S2′2-) ligands were synthesized. [OsII(PR3)2(′S4′)] [R = Ph (1), Et (2)], [OsIV(PR3)2(′S2′)2] [R = Et (3), Pr(4), Me(5), Ph(6)], [OsIV(PCy3)(′S2′)2] (7), (PHCy3)[OsIII(′S2′)2] (8a), (NMe4)[OsIII(′S2′)2] (8b), and (NBu4)2[OsIV(′S2′)3] (9b) were obtained in reactions starting from commercially available osmium compounds and the sulfur and phosphane ligands. The presence or absence of reducing solvents strongly influenced these reactions. Octahedral (3), (4), and (PHCy3)2[OsIV(′S2′)3] (9a) were characterized by X-ray structure analysis, leading to the conclusion that despite the high oxidation state of the osmium centers, innocent dithiolate ligands are present. The stabilization of the OsIV centers is traced back to S→M π donation. Close inspection of 1 and 2 revealed a large influence of the phosphane ligands on the stability of OsII thioether complexes. While 1 is reasonable stable, 2 readily gives 3 and ethylene via intramolecular ′S4′2- ligand reduction and OsIII→ OsIV oxidation. UV-Vis spectra of 3-5 indicate phosphane dissociation in solution leading to pentacoordinate [Os(PR3)(′S2′)2] complexes. This was confirmed by the synthesis of pentacoordinate [Os(PCy3)(′S2′)2] (7).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 146
    Electronic Resource
    Electronic Resource
    The Triphosphide (tBu3Si)2P3Na: Formation, X-ray and Ab initio Structure Analyses, Protonation and Oxidation to Triphosphane (tBu3Si)2P3H and Hexaphosphanes (tBu3Si)4P6⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 833-841 
    Details
    ISSN: 1434-1948
    Keywords: Silicon ; Phosphorus ; Oligophosphides and -phosphanes ; NMR spectra ; X-ray structure analysis ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The violet THF adduct (tBu3Si)2P3Na(THF)4 (1a) of the triphosphide (tBu3Si)2P3Na (1) is prepared, (i) by protolysis of the tetraphosphide (tBu3Si)2P4Na2 (2) with an equimolar amount of CF3CO2H in THF (transformation of 2 into 1), (ii) by the reaction of tBu3SiNa and the oligophosphane (tBu3SiP3)n in THF (building-down of Pn), and (iii) by the action of tBu3SiNa on PCl3 in THF (building-up of Pn). According to X-ray structural analysis, the SiPPPSi skeleton of the anionic part [tBu3SiPPPSitBu3]- of 1a is W-shaped with two P-P 11/2 bonds; in addition, 1a contains a planar deltoid P3Na backbone with the 4 THF molecules coordinated to Na. The protolysis of 1a leads to cyclotriphosphane (tBu3Si)2P3H (11), and the oxidation of 1a leads to 1,1′-bicyclotriphosphane (tBu3Si)2P3-P3(SitBu3)2 (12) as the main product and bicyclo[3.1.0]hexaphosphane (tBu3Si)4P6 (13) as an isomer of 12. The structures of 11, 12, and 13 as well as the structure of 1a have been unambiguously determined by 31P-NMR studies. Ab initio structure and energy calculations show that the acyclic P3H2- with allylic conjugation and P-P 11/2 bonds is thermodynamically more stable than the cyclic isomer whereas, in contrast, the neutral compound P3H3 prefers the cyclic form. The exceptional downfield shift of the NMR signal of the central phosphorus in 1a is in agreement with DFT NMR calculations for a model compound [H3SiPPPSiH3]Na with P-P 11/2 bonds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 147
    Electronic Resource
    Electronic Resource
    Borane-Substituted Imidazol-2-ylidenes: Syntheses, Structures, and Reactivity⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 843-849 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; Carbenes ; Carbene complexes ; Heterocycles ; Imidazoles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of the Lewis acids BH3 and BEt3 with trimethylimidazole (1) lead to the borane adducts 2a and 2b. Deprotonation of 2a with n-butyllithium results in the formation of the novel N-borane-substituted imidazol-2-ylidene anion 3a- whereas deprotonated 2b rearranges unexpectedly to the anionic compound 3b-. This can be transformed into the carbene-borane adduct 4 by methylation. The reaction of 3a- with [Mn(CO)5Br] yields the carbene complex 5. Surprisingly, 3a- attacks Fe(CO)5 at a carbon atom which leads to the iron acyl complex anion 6-. The compositions of the products follow from spectroscopic and analytical data and from X-ray structure analyses for Li(thp)+3a-, Li(thf)2+3b- and Li(thp)3+6-.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 148
    Electronic Resource
    Electronic Resource
    Neutron Diffraction Study of [K(18-crown-6)] [(PPh3)2ReH6Cr(CO)3], a Bimetallic Donor-Acceptor Complex⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 851-854 
    Details
    ISSN: 1434-1948
    Keywords: Neutron diffraction ; Donor-acceptor complex ; Bridging hydride ligand ; Rhenium ; Chromium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A neutron diffraction analysis was carried out at 120 K on a single crystal of [K(18-crown-6)][(PPh3)2ReH6Cr(CO)3] · THF in order to locate the hydride ligands. Three of the hydrides are bound terminally to the Re atom while the other three bridge the Re-Cr bond; the bridging hydrides are closer to the Re atom. This compound can be thought of as a donor-acceptor complex, with [(PPh3)2ReH6]- acting as the donor to the Cr(CO)3 fragment. Average distances and angles: Re-Cr = 2.58(1), Re-H(br) = 1.75(1), Cr-H(br) = 1.92(2), Re-H(t) = 1.69(1) Å; Re-H-Cr = 89.1(7)°. Final agreement factors: R(F) = 6.4% for 3443 reflections with I 〉 2σ(I), and R(F) = 8.3% for all data (4195 reflections).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 149
    Electronic Resource
    Electronic Resource
    Synthesis of Silylborazines and Their Utilization as Precursors to Silicon-Containing Boron Nitride⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 855-859 
    Details
    ISSN: 1434-1948
    Keywords: Borazines ; Silyl borazines ; Oligomers ; Pyrolysis ; Ceramics ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of LiSi(SiMe3)3 with Cl(Me)2B3N3(Me)3, Cl2(Me)B3N3(Me)3, (ClBNMe)3, and (ClBNH)3 result in the formation of molecular species (Me3Si)3Si(Me)2B3N3(Me)3, [(Me3Si)3Si]2(Me)B3N3(Me)3, [(Me3Si)3SiBNMe]3, and [(Me3-Si)3SiBNH]3. The new compounds have been characterized by spectroscopic techniques, and a single-crystal X-ray diffraction analysis for [(Me3Si)3SiBNMe]3 has been completed. The monomer (Me3Si)3Si(Cl)2B3N3H3 was also prepared and combined with (Me3Si)2NH in hexane to form an organic solvent soluble oligomer. Pyrolysis of this oligomer provides composites containing BN and an SiXNYCZ phase that suppresses the crystallization of BN.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 150
    Electronic Resource
    Electronic Resource
    A Trinuclear Palladium(II) Complex with Bridging 2-Hydroxyacetophenone N4-Ethylthiosemicarbazone Ligands - An Unusual Dimethylformamide Promoted Deprotonation and Aggregation (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 861-863 
    Details
    ISSN: 1434-1948
    Keywords: Trinuclear triangulo palladium complex ; 2-Hydroxyacetophenone N4-ethylthiosemicarbazone ; Dimethylformamide aggregation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray crystal structure of a palladium(II) complex of 2-hydroxyacetophenone N4-ethylthiosemicarbazone (H2Ap4E) shows it to be a triangular,trinuclear complex with bridging thiosemicarbazonato sulfur atoms. This species can be formed from a monomer on dissolution in DMF or directly from Li2PdCl4 and the thiosemicarbazone in methanol-ammonia solution.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 151
    Electronic Resource
    Electronic Resource
    Palladacycles as Reactive Intermediates (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 877-877 
    Details
    ISSN: 1434-1948
    Keywords: Correction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reference [5] on page 1576 should read as follows: [5] A special case of a 9-membered palladacycle annelated by four cyclopentane units has been reported: P. Binger, H. M. Büch, R. Benn, R. Mynott, Angew. Chem.1982, 94, 66; Angew. Chem. Int. Ed. Engl. 1982, 21 62-63.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 152
    Electronic Resource
    Electronic Resource
    Reaction of ortho-Methylbenzonitrile with Lithium N,N,N′-Trimethylethylenediamide: Assembly and Crystal Structure of a Primary Isoquinolinoamidolithium-Secondary Amine Complex (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 879-883 
    Details
    ISSN: 1434-1948
    Keywords: Isoquinoline ; Lithium ; Self-condensation ; Solid-state structure ; Solution structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The product of reaction between ortho-methylbenzonitrile (o-MeC6H4CN) and lithium N,N,N′-trimethylethylene-diamide [LiN(Me)(CH2)2NMe2], the 1:1 complex 1-lithio-amido-3-(2-methylphenyl)isoquinoline-N,N,N′-trimethylethylenediamine (1-Li·HTriMEDA), has a solid-state structure which shows a new type of (NCNLi)2 core and a solution structure in which the coordination mode of the diamine by-product varies with temperature.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 153
    Electronic Resource
    Electronic Resource
    Synthesis of Stable N′,N′,N′′,N′′-Tetramethylguanidine-Substituted σ4(P)- and σ3(P)-Organophosphorus Compounds with N-Protonated P-N Bonds - The First σ3-Phosphorus-Substituted Ammonium Salts⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 865-875 
    Details
    ISSN: 1434-1948
    Keywords: N′,N′,N′′,N′′-Tetramethylguanidine ; Triphenylmethyl ; Phosphorus-substituted ammonium salts ; Steric hindrance ; Cleavage reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dependence of the protolytic decomposition rate of phosphorus amides on the substituents at phosphorus is decribed. On treatment with HCl, the N′,N′,N′′,N′′-tetramethylguanidine(= TMG)-substituted σ4(P) compounds 5 and 9 formed salts that were protonated at the imino nitrogen atoms and were completely stable in the solid state, and surprisingly stable in solution. Even with a large excess of HCl, only the imino nitrogen atom underwent protonation, with formation of HCl2- as a counter anion, without cleavage of the P-N bond. The basicity of the imino nitrogen atom also protected σ3(P) species from electrophilic attack, and the ionic compounds 12, 14, and 20c were formed, providing examples of the first stable σ3(P) amides with one or two protonated P-N bonds. Such unusual stability is associated with steric protection by the Ph3C (= trityl) group and charge delocalization over the TMG-moiety. In contrast, MeP(TMG)2 was unstable towards HCl, whereas treatment with HSbF6 led to the phosphonium salt 24, where protonation had occurred at phosphorus. The same result was obtained when triphenylmethylphosphonous dichloride 1 was allowed to react with 3 equivalents of HTMG, forming the stable phosphonium salt 19, soluble in water, which was converted to the bicationic species 20c upon treatment with HCl. - The basicity of the tritylated phosphorus compounds was found to increase in the order 5 〈 2 〈 19 〈 13 HTMG 〈 21; the basic centre is the phosphorus atom in 21 and the imino nitrogen atom in all other compounds. The fluorinating agent Et3N · 3 HF caused rapid conversion of compound 6to 25, the nucleophilic attack of fluoride ion at phosphorus could not be prevented by the stabilizing effects mentioned. - All compounds were investigated by 1H- and 31P-NMR spectroscopy. The crystal structures of compounds 5, Ph3CP(=O)-(H)TMG, and 6, [5 · 2 HCl], were determined; 6 is protonated at the imino nitrogen, leading to a longer P-N bond [5: 161.6(2), 6: 168.7(2) pm], and the counterion is HCl2-. In the structure of 20c, [Ph3CP(TMG)2] · 3 HCl, the cation is protonated at both imino N atoms and the counterions are Cl- and HCl2- (one of each).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 154
    Electronic Resource
    Electronic Resource
    (1S,2S)-Cyclopentane-1,2-diyl-bis(phosphonous dichloride), (1S,2S)-C5H8(PCl2)2 - A Versatile Optically Active Reagent (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 885-887 
    Details
    ISSN: 1434-1948
    Keywords: Chirality ; P ligands ; Synthetic methods ; Triphosgene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of (1S,2S)-C5H8(PH2)2 (1) with OC(OCCl3)2 gave (1S,2S)-C5H8(PCl2)2 (2) as the first example of an optically active bis(phosphonous dichloride). 2 was converted to (1S,2S)-C5H8(PX2)2 [PX2 = P(OMe)2 (3), P(OPh)2 (4), P[OCH-(Me)Et-(S)]2 (5), P[2-OC10H6C10H6O-2′-(R)] (6), P(NC4H8O-cyclo)2 (7), P(C6H11-cyclo)2 (8)] by reactions with oxygen, nitrogen, and carbon nucleophiles.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 155
    Electronic Resource
    Electronic Resource
    Zirconocene-(μ-Organyl)borate Betaines Derived by Treatment of a (σ-Alkenyl)(σ-alkynyl)zirconocene Complex with Tris(pentafluorophenyl)borane⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 889-895 
    Details
    ISSN: 1434-1948
    Keywords: Zirconocene ; Metallocene cation ; Isonitrile insertion ; Isonitrile complex ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrozirconation of propyne followed by treatment with propynyllithium yields the (σ-propenyl)(σ-propynyl)zir-conocene complex 11. Its treatment with the organometallic Lewis acid B(C6F5)3 results in transfer of the σ-propynyl group from zirconium to boron followed by insertion of the alkynylborate triple bond into the zirconium carbon bond of the remaining metallaallyl cation to furnish the zirconocene-(μ-hydrocarbyl)borate betaine complex 14. This reacts with three molar equivalents of tert-butyl isocyanide to give 16. Complex 16 contains a five-membered carbocyclic ring, formed by carbon-carbon coupling of the former propenyl and propynyl groups with the C≡N-R reagent, to which a (η2-iminoacyl)(ĸ-tert-butyl isocyanide)zirconocene moiety is attached. Complex 16 was characterized by an X-ray crystal structure analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 156
    Electronic Resource
    Electronic Resource
    Chelate-Assisted Oxidative Addition of Phenyl- and Alkyltin Groups to Nickel and Platinum (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 897-903 
    Details
    ISSN: 1434-1948
    Keywords: Platinum ; Nickel ; Stannyl complexes ; Oxidative addition ; Tin ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Ni(COD)2 (COD = 1,5-cyclooctadiene) with two equivalents of Ph2PCH2CH2SnPh3 or of (Ph3P)2Pt(C2H4) with two equivalents of Ph2PCH2CH2SnR3 (R = Ph, Me, Bu) results in the immediate formation of the complexes (R3SnCH2CH2Ph2P)M[PPh2CH2CH2SnPh2(M-Sn)](R) (M = Ni, Pt) with a cis arrangement of the two phosphorus atoms. The structure of (Me3SnCH2CH2Ph2P)Pt[PPh2CH2-CH2SnMe2(Pt-Sn)](Me) was confirmed by an X-ray structure analysis. In the presence of PPh3, this complex shows dynamic behavior in solution due to Ph2PCH2CH2SnMe3/PPh3 exchange. When the phosphanylalkylstannanes Ph2PCH2CH2SnPh3-xMex (x = 1, 2) are employed in the reaction with Ni(COD)2 or (Ph3P)2Pt(C2H4), the Sn-Ph groups are more prone to oxidative addition than the Sn-Me groups. When Ni(COD)2 is treated with one equivalent of Ph2PCH2CH2SnPh3 and PR′3 (PCy3 or PMe2Ph) each, the complexes (R′3P)M(PPh2CH2CH2SnPh2)(Ph)(M-Sn) are formed. Heating of (Ph3SnCH2CH2Ph2P)Ni[PPh2-CH2CH2SnPh2(Ni-Sn)](Ph) to 70 °C induces the oxidative addition of a Sn-Ph group of the dangling ligand, and cis-Ni[PPh2CH2CH2SnPh2(Ni-Sn)]2 is obtained. The same complex is formed upon reaction of Ni(COD)2 with Ph2PCH2CH2SnPh2H. Reaction of Ni(COD)2 with Ph2PCH2CH2SnMe3 results in the immediate formation of trans-Ni[(PPh2CH2CH2SnMe2(Ni-Sn)]2.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 157
    Electronic Resource
    Electronic Resource
    Phosphane Complexes of Alkaline Earth Metals (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 905-911 
    Details
    ISSN: 1434-1948
    Keywords: Phosphane complexes ; Alkaline earth metal compounds ; Phosphanomethanides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of lithium[bis(dimethylphosphanyl)(trimethyl-silyl)methanide] Li[(PMe2)2C(SiMe3)] with BeCl2 gave the homoleptic compound Be[(PMe2)2C(SiMe3)]2 (5) with four beryllium-phosphorus bonds constituting a distorted tetrahedron around the beryllium center. The reaction of MgCl2 with Li[(PMe2)2C(SiMe3)] resulted in the formation of the bis-chelate complex Mg[(PMe2)2C(SiMe3)]2 · 2 THF (7), where the distorted cis-octahedral magnesium center is additionally coordinated by two THF ligands. In the reaction of 7 with an additional equivalent of Li[C(PMe2)2(SiMe3)], THF is released and the magnesate anion {Mg[(PMe2)2C-(SiMe3)]3}- (8) was obtained. This compound is not only the first reported hexacoordinated magnesate, but also the first magnesium compound with six magnesium-phosphorus bonds. With CaCl2 and Li[C(PMe2)2(SiMe3)], a heptacoor-dinated complex Ca[(PMe2)2C(SiMe3)]2 · 3 THF (10) with three coordinating THF ligands was isolated. The complexes were characterized using 9Be{1H}-, 31P{1H}-, 1H-, 13C{1H}-NMR spectroscopy, and elemental analysis and by X-ray diffraction. The neutral compounds are highly soluble in nonpolar solvents.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 158
    Electronic Resource
    Electronic Resource
    Diastereoselective Synthesis of Chiral (Triazolinylidene)rhodium Complexes Containing an Axis of Chirality (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 913-919 
    Details
    ISSN: 1434-1948
    Keywords: Chiral carbenes ; Carbene complexes ; Rhodium complexes ; Axial chirality ; Asymmetric hydrosilylation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deprotonation of chiral triazolium salts 1 and reaction of the resulting nucleophilic carbenes with [(COD)RhCl]2 or [(NBD)RhCl]2 afforded square-planar complexes 2-6 in yields of 65-95%. The complexes contain an axis of chirality and a diastereomeric excess of up to 97% was achieved. The relative and absolute configurations of these complexes were determined by NMR spectroscopic investigations and X-ray structure analysis. The application of the rhodium(COD) complexes as catalysts in an asymmetric hydrosilylation reaction has been examined, resulting in enantiomeric excesses of up to 44%. Similar results were achieved for aromatic and aliphatic ketones and a nonlinear temperature effect (principle of isoinversion) was observed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 159
    Electronic Resource
    Electronic Resource
    A Methylene-Bridged Dialuminium Compound as a Chelating Lewis Acid: Complexation of Nitrite and Nitrate Anions by R2Al-CH2-AlR2[R = CH(SiMe3)2]⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 921-926 
    Details
    ISSN: 1434-1948
    Keywords: Aluminium ; Chelates ; Lewis acids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sodium nitrite (NaNO2) dissolves readily in THF, when the methylene-bridged dialuminium compound R2Al-CH2-AlR2 [R = CH(SiMe3)2] 1 with two coordinatively unsaturated aluminium atoms is added. Compound 1 reacts as a chelating Lewis acid, and, as shown by a crystal structure deter-mination of the [Na([18]crown-6)(Et2O)]+ derivative 5c, a compound (5) is formed, in which one oxygen atom and the nitrogen atom of the nitrite ion are each coordinated by one aluminium atom to form a five-membered Al2CNO hetero-cycle. The second oxygen atom of the nitrite anion is not affected. Similarly, lithium nitrate (LiNO3) reacts with 1 to yield a THF soluble product (6a). Single crystals were obtain-ed of the [Li(N,N′,N′′-trimethyltriazinane)2]+ derivative 6c, whose structure shows each aluminium atom to be coordinated by one oxygen atom of the nitrate ion to give a six-membered Al2CNO2 heterocycle.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 160
    Electronic Resource
    Electronic Resource
    Bis(tetramethylpiperidino)aluminum Halide Adducts tmp2AlX · Do and Tetrahaloaluminates of Tricoordinated Aluminum Cations [tmp2Al(Do)]AlX4 (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 927-939 
    Details
    ISSN: 1434-1948
    Keywords: Bis(tetramethylpiperidino)aluminum halide complexes ; Tricoordinated aluminum cations ; 27Al-NMR spectroscopy ; X-ray crystal structure analysis ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Upon treatment with Lewis bases Do (Do = pyridine bases or THF), the Lewis acids tmp2AlX (X = Cl, Br, I) are converted exclusively to the monoadducts tmp2AlX · Do (2-4). The Al-X bonds of these addition compounds are considerably elongated, indicating a tendency towards the formation of ionic species [tmp2Al(Do)]X. Due to the steric requirements of the bulky tmp ligands, addition of an excess of the Lewis base does not force these compounds to form tetracoordinated aluminum cations [tmp2Al(Do)2]+ or pentacoordinated adducts tmp2AlX · Do2. Attempts to prepare ionic representatives by reaction of tmp2AlX · Do with “ate” complexes of comparatively low nucleophilicity [MY = NaBPh4, AgBPh4, LiB(C6F5)4, AgBF4, AgOtos] result in phenylation products [e.g. tmp2AlPh (5a) and BPh3 · py (5b)] or tetracoordinated addition compounds tmp2AlY · Do (Y = anion). However, addition of one equivalent of AlX3 (X = Br, I) initiates halide abstraction with formation of the ionic [tmp2Al(Do)]AlX4 species 6a-f, as indicated by 27Al-NMR data and conductivity measurements. Solid [tmp2Al(py)]AlI4 (6b) decomposes readily into tmpAII2 and tmpAlI2 · py (7c). Addition of non-polar aliphatic solvents to solutions of [tmp2Al(Do)]AlX4 (6) leads to slow decomposition into tmp2AlX and AlX3 · Do (7a-b, d). This also occurs in polar donor solvents, where compounds AlX3 · Do are favoured due to the formation of penta- or hexacoordinated species AlX3 · Do · Solvn (n = 1, 2). Semiempirical AM1 calculations reveal the gas-phase stability of the tricoordinated bis(tmp)aluminum cation in the salt [tmp2AlPy]AlCl4 as the only representative in a series of calculated aluminum cations [(R2N)2AlPy]AlCl4 (R2N = Me2N, Et2N, iPr2N, tmp). According to these calculations, the stability of a given cation increases when tetrachloroaluminate is replaced by tetraiodoaluminate. Ab initio calculations have been performed on two cations [(H2N)2Al(Do)]+ (Do = NH3, py) and indicate very short Al-N bond lengths owing to ionic bonding contributions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 161
    Electronic Resource
    Electronic Resource
    1,2-Diphosphetes with Unusual Structures - A Quantum Chemical Investigation of Bonding Properties⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 951-955 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Phosphorus ; Strained molecules ; Substituent effects ; Pericyclic reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: According to quantum chemical calculations at an ab initio level parent 1,2-diphosphete is slightly more stable than its corresponding 1,4-diphosphabutadiene structural isomer. The quantum chemical calculations indicate that substituents at phosphorus and to a much less extent at carbon exert strong influences on the equilibrium geometries of 1,2-diphosphete structures: π donors at phosphorus strongly elongate the P-P bond while electronegative substituents at phosphorus increase the interflap angle of the four-membered ring systems, bringing an envelope conformation to the fore. The lengthening of the P-P bond gives rise to a Möbius-type delocalization within the ring moiety.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 162
    Electronic Resource
    Electronic Resource
    Intramolecular Luminescence Quenching in Amino Acid Bridged Ruthenium(II)-Copper(II) Complexes with Negligible Ground-State Coupling (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 957-963 
    Details
    ISSN: 1434-1948
    Keywords: Amino acids ; Bioinorganic chemistry ; Copper ; Luminescence ; Ruthenium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of heterobimetallic complexes [{Ru(bipy)2}m-AA{Cu(phen)(H2O)}](PF6)3 (m-AA = Nω-(4-carbonyl-4′-methyl-2,2′-bipyridyl)-L-α,ω-diamino acid; diamino acid (AA): 1b, L-2,3-diaminopropionic acid; 2b, L-2,4-diaminobutyric acid; 3b, L-ornithine, 4b, L-lysine) has been synthesized and characterized starting from the 2,2′-bipyridineruthenium(II)-substituted amino acids [{Ru(bipy)2}m-AA-αN-tBoc]2+ (αN-tBoc-1a-4a, αN-tBoc = Nα-tert-butoxycarbonyl). The metal centers in 1b-4b are bridged by insulating alkyl chains. Consequently, spectroscopic and electrochemical investi-gations confirmed the absence of any appreciable ground-state coupling between ruthenium(II) and copper(II). However, the luminescence of 1b-4b is significantly quenched compared to that of the parent compounds 1a-4a. Quenching was found to proceed only intramolecularly and to be most efficient in 1b with the shortest alkyl spacer. Equilibrium constants for the formation of 1b-4b were determined from luminescence titrations of the respective ruthenium-substituted amino acid with [Cu(phen)(NO3)2]. The complexes 2b-4b (K = 1.61-2.08 × 107M-1) were found to be significantly more stable than 1b (K = 5.7 × 106M -1). This is explained by a stronger electrostatic repulsion between the two metal centers in the latter compound.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 163
    Electronic Resource
    Electronic Resource
    Structural Chemistry of Lithium Tetrahydroborate Ether Solvates⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 941-949 
    Details
    ISSN: 1434-1948
    Keywords: Lithium tetrahydridoborate diethyl ether (1:1) ; Lithium tetrahydridoborate diveron (1:1) ; Lithium tetrahydridoborate dimethoxyethane (1:2) ; Lithium tetrahydridoborate triglyme (1:1) ; Lithium tetrahydridoborate tetrahydrofuran (1:3) ; Lithium tetrahydridoborate 1,3-dioxolane (1:1) ; Hydride-bridge bonding ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: LiBH4 · OEt2 (1) and LiBH4 · O(Me)CMe3 (2) form double-stranded chains in the solid state. While 3 hydrides of the BH4 group in 1 bind to three different Li atoms through Li···H-B interactions, the fourth H atom interacts with three adjacent Li centers. In contrast, in compound 2 there are two single Li···H-B bonds and two doubly bridging hydrogen atoms, the latter again interacting with three lithium centers. Moreover, the arrangements of the ether molecules in 1 and 2 are different. LiBH4 · 2 DME (3) (DME = dimethoxyethane) forms a molecular lattice, in which the BH4- anions are present in Li···H2BH2 bridges. The same structural feature is present in LiBH4 · TG (4) (TG = triglyme = triethylene glycol dimethyl ether), but the TG molecule coordinates to two Li centers through two of its four oxygen atoms in such a manner that a chain structure results. The compound LiBH4 · 3 THF (5) exists as discrete molecules in the lattice. Its BH4- anion is triply bridging to the Li center. In contrast, LiBH4·C3H6O2 (6) (1,3-dioxolane) is polymeric. Due to the presence of two μ22-BH4 groups, a chain of the type ···Li(H2BH2)Li(H2BH2)··· is formed, and the 1,3-dioxolane molecules connect the chains through Li-O coordination to form a three-dimensional array. In spite of the variations in the bonding of the BH4 group to Li centers, the Li atoms are hexacoordinated in 3 to 6 but are heptacoordinated in 1 and 2.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 164
    Electronic Resource
    Electronic Resource
    Substituted Cyclopentadienides of Magnesium from the Reaction of Dialkylmagnesium with Fulvenes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 965-971 
    Details
    ISSN: 1434-1948
    Keywords: Cyclopentadienes ; Magnesium ; Metalations ; NMR spectroscopy ; Sandwich complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of n/sec-dibutyl magnesium with 6-methyl-6-phenyl- and 6,6-dicyclopropylfulvene gives the β-hydride transfer products 1,1′-bis(1-phenylethyl)- and 1,1′-bis-(dicyclopropylmethyl)magnesocene, respectively. The latter crystallizes in the eclipsed conformation, whereas the first one shows an anti conformation in the solid state. Dimethyl-magnesium deprotonates 6-methyl-6-phenylfulvene with formation of 1,1′-bis(1-phenylethen-1-yl)magnesocene, which decomposes upon isolation. The deprotonation of 6,6-dicyclopropylfulvene with MgMe2 in thf solution yields [bis(tetrahydrofuran-O)][iro{cyclopropane-1,2′(1′-η5-cyclopentadienyl-1′,3′,3′-tricyclopropyl-1′,2′,3′,3a′-tetrahydropentalene)}-3a′-6′-η2-enyl]magnesium. In the absence of β-hydrogen atoms at the organometallic reagent as well as at the fulvene the addition reaction is the only possible reaction pathway. Thus, one Mg-C bond of MgMe2 adds to tetramethylfulvene to give quantitatively dimeric methylmagnesium ethyltetramethylcyclopentadienide. The bridging methyl groups are sterically shielded against further attack of the fulvene.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 165
    Electronic Resource
    Electronic Resource
    Cyclopentadienone Cyclopentadienediyl Diselenoketals (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 973-976 
    Details
    ISSN: 1434-1948
    Keywords: Cyclopentadiene ; Selenium ; Ketal ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of di-tert-butylcyclopentadiene with excess potassium tert-butoxide in the presence of elemental selenium leads to cyclopentadienes bridged by two or three selenium atoms through one or two diselenoketal functionalities. 2,5,4′,6′-Tetra-tert-butyl-5′H-spirocyclopentane-1,2′-cyclopenta[b][1,3]diselena-2,4-diene (1) and 1,3,5,7-tetra-tert-butyl-3a,7a-dihydro-3a,7a-epi-selenodicyclopenta[b,e][1,4]diselenine (2) have been characterized by single-crystal X-ray diffraction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 166
    Electronic Resource
    Electronic Resource
    Synthesis and Properties of Silver(I) and Copper(I) Helicates with Imine-Bridged Oligobipyridine Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 977-982 
    Details
    ISSN: 1434-1948
    Keywords: Helicates ; Oligobipyridine ligands ; Self-recognition ; NMR titration ; Self-assembly ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oligobipyridine ligands containing one or two imine bridges were found to form double helicates by treatment with copper(I) or silver(I). The properties of the complexes are similar to those of oxapropylene-bridged oligobipyridines. Titration of a mixture of the bis(bipyridine) and the tris(bipyridine) ligands with silver(I) hexafluorophosphate showed that helicates formed with strict self-recognition.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 167
    Electronic Resource
    Electronic Resource
    Generation of 1,3-Dithia-, 1-Selena-3-thia-, and 1,3-Diselena-2-tellurole by Neutralization-Reionization Mass Spectrometry⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 983-987 
    Details
    ISSN: 1434-1948
    Keywords: Telluroles ; Neutralization-reionization mass spectrometry ; DFT calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,2-Dichloro-1,3-dichalcogena-2-telluroles of sulfur and selenium, C6H4[XTe(Cl)2Y] with X, Y = S, Se, serve as precursors to generate the cation radicals of 1,3-dichalcogena-2-telluroles C6H4[XTeY]+• as well as the corresponding neutral counterparts by means of neutralization-reionization mass spectrometry. These neutral 2-telluroles are intrinsically stable for at least 1 μs in the gas phase. The most abundant fragmentation channel at the neutral and cationic stages is due to loss of atomic tellurium to afford the corresponding benzo-1,2-dichalcogena-cyclobutenes. For the latter, partial isomerization to the related dichalcogena-ortho-quinones is indicated by the mass-spectrometric fragmentation pattern.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 168
    Electronic Resource
    Electronic Resource
    Synthesis of Gold(I) and Gold(II) Complexes with Diphenyl(trimethylsilylmethyl)phosphane (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 989-992 
    Details
    ISSN: 1434-1948
    Keywords: Gold(I) ; Gold(II) ; Diphenyl(trimethylsilylmethyl)phosphane ; Ligand effects ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of diphenyl(trimethylsilylmethyl)phosphane with [AuCl(tht)] affords the gold(I) complexes [AuCl(PPh2-CH2SiMe3)] (1) or [Au(PPh2CH2SiMe3)2]Cl (2). An X-ray study of 1 does not reveal any Au···Au interaction. Treatment of [Au(tht)2](CF3SO3) or [Au(tht)(PPh3)](CF3SO3) with diphenyl(trimethylsilylmethyl)phosphane results in the displacement of the thioether ligands to give the ionic complexes [Au(PPh2CH2SiMe3)2](CF3SO3) (3) or [Au(PPh2-CH2SiMe3)(PPh3)](CF3SO3) (4), the latter mixed with the symmetrical derivatives [Au(PPh2R)2](CF3SO3) (R = Ph, CH2-SiMe3). The molecular structure of complex 3 has been established by X-ray diffraction and shows an antiperiplanar arrangement of the two PR2R rotors in the solid state. The reaction of the phosphane ligand with [Au2{μ-(CH2)2-PPh2}2(tht)2](ClO4)2affords the dinuclear gold(II) complex [Au2{μ-(CH2)2PPh2}2(PPh2CH2SiMe3)2](ClO4)2 (5).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 169
    Electronic Resource
    Electronic Resource
    Synthesis and Structural Characterization of Rare Earth Metal Disulfonamide Complexes⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1009-1014 
    Details
    ISSN: 1434-1948
    Keywords: Rare earth metals ; Lanthanides ; Chelating sulfonamides ; Silylamide route ; C2 symmetry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of rare earth silylamides Ln[N(SiHMe2)2]3(thf)n [n = 1 for Sc (1a); n = 2 for Y (1b), La (1c), Nd (1d)] with trans-1,2-bis(2,4,6-triisopropylbenzenesulfonamido)cyclohexane (H2L, rac-2) in toluene at ambient temperature proceeds via an extended silylamide route, affording highly soluble complexes Sc(L)[N(SiHMe2)2] (3) and Ln(L)[N(SiHMe2)2](thf) (4a-c) in excellent yields. An X-ray crystallographic study performed on the solvent-free, dinuclear yttrium derivative 5 revealed an unusual μ2,η4:η1-coordination of the disulfonamide ligand, involving bridging S=O groups. In solution, equilibria between dimeric and monomeric forms, dependent on the presence of a donor molecule, were observed by NMR techniques.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 170
    Electronic Resource
    Electronic Resource
    Synthesis, Molecular Structure, Fluxional Behavior, and Tricarbonyliron Transfer Reactions of (η4-1-Azabuta-1,3-diene)tricarbonyliron Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 993-1007 
    Details
    ISSN: 1434-1948
    Keywords: Azabutadienes ; Tricarbonyliron complexes ; Transfer reagents ; Molecular structure ; Fluxionality ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The (η4-1-azabuta-1,3-diene)tricarbonyliron complexes 10 are easily prepared in high yield by condensation of the corresponding arylamines 7 with the cinnamaldehydes 8 and subsequent ultrasound-promoted complexation of the resulting 1-azabuta-1,3-dienes 9 with nonacarbonyldiiron. The complexes 10 are shown to represent excellent reagents for the transfer of the tricarbonyliron fragment onto cyclohexa-1,3-diene (1a). The structural characterization for the complexes 10 is achieved by IR, 1H-NMR, and 13C-NMR spectroscopy, as well as X-ray crystallography of 10b, 10c, and 10l. Using variable temperature 13C-NMR spectroscopy the fluxionality of the complexes 10a, 10b, 10c, 10e, and 2 is investigated and the activation barrier for the turnstile rotation of the tricarbonyliron fragment is determined. The transfer reaction and the structural factors influencing the transfer of the tricarbonyliron fragment are extensively investigated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 171
    Electronic Resource
    Electronic Resource
    Formation of a Stable Adduct of Ethoxycarbonyldithiocarbamic Acid and a Dimer of Ethoxycarbonyl Isothiocyanate (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1025-1028 
    Details
    ISSN: 1434-1948
    Keywords: Sulfur heterocycles ; Hydrolyses ; Isothiocyanate ; Dithiocarbamic acids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of ethoxyxcarbonyl isothiocyanate with water in the absence of a solvent has yielded the new compound [EtO2CN=CS2C{N(H)CO2Et}{S2CN(H)CO2Et}] (1) in 76% yield that has been isolated in a crystalline form that con-tains one equivalent of ethoxyxcarbonyl isothiocyanate. Compound 1 can be viewed as an adduct of a dimer of EtO2CN=C=S and the dithiocarbamic acid 2. Compound 1 dissociates in solution to yield 2 and free ethoxyxcarbonyl isothiocyanate. Compound 2 can be isolated chromatog-raphically, but it is slowly oxidized when allowed to stand in the open air to form the thiuram disulfide 3. Compounds 1 and 3 were characterized crystallographically. Compound 1 contains an imino-substituted dithietane ring with a dithiocarbamate substitutent bonded to one of the ring carbon atoms. Compound 3 is a thiuram disulfide which has C2 crystallographic symmetry.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 172
    Electronic Resource
    Electronic Resource
    π-Bond vs. Agostic Interaction in Three-Coordinated Alkoxy and Thiolate Derivatives of Aluminium, Boron and Cationic Carbon - An ab initio Study of H2X-YR Systems (X = Al, B, C+; Y = O, S; R = H, CH3) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1015-1023 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; π interactions ; Agostic interactions ; Electronic structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational barriers and π conjugation effects have been studied in H2X-YR systems (X = Al, B; Y = O, S; R = H, CH3) by means of ab initio calculations at the MP4/6-311G**//MP2/6-311G** level. In non-substituted systems H2X-YH, it is shown that the rotational barrier depends on three factors: (i) π conjugation strength between the X vacant p orbital and the Y p-lone pair; (ii) the opening ability of the Y-valence angle and (iii) a possible direct interaction between X and the Y hydrogen substituent. The conjugation stabilization has been estimated through Valence Bond calculations and is found to decrease in the order BO (22.6 kcal/mol), BS (16.6 kcal/mol), AlO (10.2 kcal/mol), and AlS (8.1 kcal/mol). Study of the methylated systems confirm the results found in unsubstituted species. The most important feature is the location of a deconjugated secondary minimum for H2B-SCH3 species. An acute B-S-C angle (69.6°) is found, thus evidencing a direct H···B agostic interaction with a four-membered (BSCH) heterocycle. To further evidence our analysis, additional calculations have been performed on carbocationic species H2C+-YR (Y = O, S; R = H, CH3) for which the H2C+ moiety is a strong π acceptor. As expected, the C+-O and C+-S conjugation are strong (about 60 kcal/mol). Only two minima have been located for the H2C+-OCH3 species. In the sulfur case, the Potential Energy Surface (PES) is more complicated and six stationary points have been characterized. A strong agostic interaction is found for a secondary deconjugated minimum for which an hydrogen symmetrically bridges the two carbon atoms. A schematic energy profile connecting the various extrema is given for this cationic species.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 173
    Electronic Resource
    Electronic Resource
    1,2-Bis[trifluorosulfur(IV)]tetrafluoroethane F3S-CF2-CF2-SF3: A Bifunctional Molecule with Two Fluoroamphoteric Sulfur Centers⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1035-1039 
    Details
    ISSN: 1434-1948
    Keywords: α,ω-Bis(trifluorosulfur)perfluoroalkanes ; α,ω-Bis(fluorosulfinyl)alkanes ; Fluorosulfur anions ; Fluorosulfur cations ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound (-CF2-SF3)2 (2) is prepared from (-CF2-SCl)2 (1) and F2 at -90 °C in 83 % yield. Reaction of 2 with CsF and TASF yields Cs[(-CF2-SF3)2F] (8), TAS [(-CF2SF3)2F] (9) and (TAS)2[(-CF2-SF4)2] (10). Fluoride-ion abstraction yields [(-CF2SF2)2F] [AsF6] (6), BF3-catalysed solvolysis in SO2 gives [-CF2-S(O)F]2 (4), and CsF-catalysed oxidation with F2 leads to the previously reported (-CF2-SF5)2 (11). Ab initio calculations of the molecular structures of 2 and the related methane derivative F2C(SF3)2 are reported.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 174
    Electronic Resource
    Electronic Resource
    Novel Syntheses of Mono- and Bisphosphonated Aromatic Phosphanes by Consecutive Pd-Catalyzed P-C Coupling Reactions and Nucleophilic Phosphanylation - X-ray Structure of Ph2P-C6H4-m-PO3Na2 · 5.5 H2O · iPrOH (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1029-1034 
    Details
    ISSN: 1434-1948
    Keywords: Pd-catalyzed P-C coupling ; Nucleophilic phosphanylation ; Mono- and bisphosphonated phosphanes ; Monoesters ; Water solubility ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The triphenylphosphane derivatives 2a and 5, bearing one and two phosphonic ester groups, are accessible in high yields by consecutive Pd-catalyzed P-C coupling reactions of p-bromoiodobenzene with Ph2PH and PhPH2, respectively, and then with diethyl phosphite. Ester hydrolysis yields the highly water-soluble sodium salts of mono- and bis-phosphonated triphenylphosphane, 3a and 6, respectively. On reaction of the p- and m-fluorophenylphosphonic diethyl esters 7a, 7b with Ph2PK and subsequent ester hydrolysis the isomeric disodium (diphenylphosphano)phenylphosphonates 3a, 3b were obtained. The X-ray structure of Ph2P(C6H4-m-PO3Na2) · 5.5 H2O · iPrOH (space group Cmc21) has been determined. In the solid state, it forms a layer structure with hydrophilic (PO32-, H2O, iPrOH) and hydrophobic (Ph2P) compartments, in which the PO32- anionic groups are not engaged in coordination of the sodium cations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 175
    Electronic Resource
    Electronic Resource
    On the Ambident Behaviour of Dicyanmethanidonitrite; Syntheses and Characterization of Complexes of the Type [M{N(O)C(CN)2}(PPh3)n] (M = CuI, AgI; n = 2, 3) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1051-1055 
    Details
    ISSN: 1434-1948
    Keywords: Silver ; Copper ; Dicyanmethanidonitrite ; Coordination modes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes of the type [M{N(O)C(CN)2}(PPh3)n] (M = CuI, AgI, n = 2, 3) were synthesized by metathesis of K[N(O)C(CN)2] and [M(NO3)(PPh3)n]. The complexes were characterized by 13C-, 31P-NMR and IR spectroscopy and elemental analyses. The crystal structures of [M{N(O)C(CN)2}(PPh3)2]2 (M = CuI, AgI) have been determined by X-ray diffraction. Depending on the metal atom in the complexes [M{N(O)C(CN)2}(PPh3)3] the ionic ligand is coordinated via the central nitrogen (copper) or the oxygen atom (silver). In addition the two copper and silver complexes [M{N(O)C(CN)2}(PPh3)2]2 are not isostructural but have quite different structures. For M = Cu the two copper atoms are doubly bridged by two NCCN sequences, forming an approximately planar Cu(NCCN)2Cu ring. On the other hand, in the homologous silver derivative the metal atoms are also doubly bridged, but by two NO groups, thus forming a planar six-membered ring.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 176
    Electronic Resource
    Electronic Resource
    Conformational Flexibility of the Square-Pyramidal Coordination Cap in a Series of Octahedral Nickel(II) Pentaamine Complexes - Magnetochemical Characterization of the Singly μ-Cl-Bridged Nickel(II) Dimer [(pyN4)Ni-Cl-Ni(pyN4)](PF6)3 [pyN4 = 2,6-Bis(1′,3′-diamino-2′-methylprop-2′-yl)pyridine] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1041-1049 
    Details
    ISSN: 1434-1948
    Keywords: Tetrapodal pentadentate ligand ; Square pyramidal coordination cap ; Pentaamine ; Nickel(II) complexes ; Magnetochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The architecture of the tetrapodal pentaamine ligand 2,6-bis(1′,3′-diamino-2′-methylprop-2′-yl)pyridine (pyN4, 1) allows it to coordinate to nickel(II) as a square pyramidal coordination cap. The pyridine nitrogen atom occupies an apical position of the coordination octahedron, while four equivalent pendent primary amino groups occupy the equatorial positions, with a sixth coordination site remaining for a monodentate ligand. Exchange of this ligand is facile, and a series of complexes [(1)NiX]n+ (X = OH2, OClO3, NCS, N3, {Cl-Ni(pyN4)}) has been prepared and characterised by elemental analysis, IR and UV/Vis spectroscopies (as applicable), and X-ray structure determination. While the solid state structures show varying degrees of distortion of the ligand cap 1 from C2v symmetry, a polynucleating coordination mode has not been observed. The ligand enables the synthesis of dinuclear nickel(II) complexes containing a single bridging ligand, as exemplified by the singly -chloro bridged complex [(1)Ni-Cl-Ni(1)](PF6)3. This complex has an antiferromagnetically coupled ground state of total spin ST = 0, as determined from variable-temperature magnetic susceptibility measurements.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 177
    Electronic Resource
    Electronic Resource
    Reaction of a Stable Silylene with Divalent Group 14 Compounds (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1067-1070 
    Details
    ISSN: 1434-1948
    Keywords: Silylene ; N Heterocycles ; Carbene analogs ; Tin ; Subvalent compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the stable silylene 1 (L′Si:) with CO, SnCl2, PbCl2, the stable carbene L′C: (2) and the stable germylene L′Ge: (3) was investigated as a possible approach for the synthesis of hetero-polysilanes (poly-carbosilanes, poly-germasilanes, poly-stannasilanes). The silylene 1 was found to be inert towards all substrates except SnCl2 and PbCl2. Reaction with SnCl2 led to the formation of the yellow, tris(silyl)stannane [(L′SiCl)3SnCl] (5) and elemental tin. The photolabile (5) was characterized by multinuclear NMR (1H, 13C, 29Si, 119Sn) and single crystal X-ray diffraction: C30H60Cl4N6Si3Sn, M = 849.60, orthorhombic, space group Pca21. The bond angles of 115.89 ° (ave. Si-Sn-Si) and 101.87 ° (ave. Cl-Sn-Si) show a slightly flattened tetrahedral geometry around the tin atom. - Thermolysis of 5 at 100 °C led to the deposition of thin films of tin; photolysis resulted in the formation of tin powder. All thermolysis products could be isolated and were characterized as SnCl2, elemental tin, L′Si: (1), L′SiCl2 (6) and the new disilane L′Si(Cl)-(Cl)SiL′ (7). Photolysis led to a reduced product spectrum (formation of Sn + SnCl2 + 7). Reaction of 1 with PbCl2 gave elemental lead and L′SiCl2 as the only products.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 178
    Electronic Resource
    Electronic Resource
    The 1,3-Sn2O2-Heterocycle as a Ligand in Organometallic Compounds - Dimerization of the Inidene Species [{(CO)5M}2SnOR]- (M = Cr, W) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1057-1066 
    Details
    ISSN: 1434-1948
    Keywords: Pentacarbonylmetal-tin bonding ; Alkoxytin compounds ; Inidene compounds ; 119Sn NMR ; Bonding ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dimerized inidene complexes [(CO)5M-Sn(OR)-M(CO)5]22- (M = Cr, W; R = Et, iPr), 1, are obtained from [{(CO)5M}2SnCl2]2- by different routes. Dimerization occurs via alkoxy-donor tin-acceptor bonding by which a planar Sn2O2 ring is formed. The Sn-{M(CO)5} bonds are made in a plane vertical to this ring such that, with the R-O groups being almost coplanar with the Sn2O2 ring, the overall geometry of the compounds shows idealized D2h symmetry. - The 119Sn-NMR resonances of 1 are found at rather low fields (M = Cr: δ ≈ 1400; M = W: δ ≈ 1170) indicating a low-lying tin-centered orbital in the LUMO range. Correspondingly EHT analyses show that the 3-center-4π system, which characterizes monomeric inidene species [LnM-E(X)-MLn]n, is still prevalent in the dimeric species 1. The low-lying π*-type LUMOs of 1 are the rationale for the observed 119Sn-NMR low-field shifts of 1. The dimeric compounds 1 react with 2,4-pentanedione to form chelate compounds of the same type as those characteristically obtained from monomeric inidene complexes: [{(CO)5Cr}2SnOEt]22- (1a) reacts to give [{(CO)5Cr}2Sn(acac)]- (2). The experimental results are verified by X-ray analyses in addition to the usual spectroscopic and analytical investigations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 179
    Electronic Resource
    Electronic Resource
    Preparation, Structures, and Properties of Dinuclear Ni and Pd Complexes of Tridentate Amine-Chalcogenolate Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1071-1077 
    Details
    ISSN: 1434-1948
    Keywords: Dinuclear complexes ; Nickel ; Palladium ; Amine-thiolate ligands ; Amine-selenolate ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation and characterization of dinuclear NiII and PdII complexes of the tridentate amine-chalcogenolate ligands 4-tert-butyl-2,6-di(aminomethyl)thiophenol (4a) and 4-tert-butyl-2,6-di(aminomethyl)selenophenol (4b) are re-ported. Reaction of 4a,b with Ni(ClO4)2·6 H2O or (COD)PdCl2 in a 1:1 molar ratio yields 1:1 complexes of composition [M2(L)2][BPh4]2·CH3CN·CH3OH [M = Ni, L = 4a,b (5a,b); M = Pd, L = 4a,b (6a,b)]. The palladium complex 6a is isomorphous with 5a as shown by X-ray crystal structure analysis. NMR studies reveal that both complexes retain their solid-state structure in solution and that the selenolate complexes are isostructural with the thiolate complexes. All complexes undergo electrochemically reversible one-electron transfer processes in the potential range -1.0 to -0.8 V vs. SCE ascribed to metal-centered reductions with formation of mixed-valent MI,II species [M2(L)2]+. Further reduction at more negative potentials then leads to the neutral [M2(L)2] species, which are not stable on the time scale of the CV experiment. The spectroscopic properties of the thiolate and selenolate complexes are very similar indicating electronically similar properties of the tridentate amine-chalcogenolate ligands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 180
    Electronic Resource
    Electronic Resource
    Complexes of Azaphospholes: Synthesis and Structure of Pentacarbonyl-(η1)-2-phosphaindolizine)chromium(0), -molybdenum(0), and -tungsten(0) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1079-1086 
    Details
    ISSN: 1434-1948
    Keywords: Phosphorus heterocycles ; P ligands ; Transition metals ; Carbonyl complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex chemical behaviour of 2-phosphaindolizines 1 (1,3-azaphospholo[1,5-a]pyridines) towards metal carbonyl compounds was studied. (η1-2-Phosphaindolizine)M(CO)5 complexes 2-4 (M = Cr, Mo, W) were formed from 1 and [(THF)M(CO)5], the cis-L2Cr(CO)4 complex 5f from 1f and tetracarbonyl(norbornadiene) chromium(0). The reaction of 2-phosphaindolizines 1e, 1f, or 1g with tricarbonyl(cycloheptatriene)molybdenum(0) or tricarbonyl(mesitylene)tungsten(0) yielded σ-complexes of the types L2M(CO)4or L3M(CO)3 rather than isolable π-complexes. In one case a strong upfield signal (δ31P = 6.1) was observed with a coordination shift of Δδ = -161.7, which is typical for π-coordination. Prolonged reaction or work-up led, however, to dismutation yielding 1g and the fac-L3Mo(CO)3 complex 6g. X-ray structure analysis of 2a indicates an increased 10π-delocalization compared with 1a and a changed conformation of the acyl substituent. The influence of substituents and metals on the 31P and 13C complexation chemical shifts and coupling constants is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 181
    Electronic Resource
    Electronic Resource
    Cation Stabilities, Electrophilicities, and “Carbene Analogue” Character of Low Coordinate Phosphorus Cations (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1087-1094 
    Details
    ISSN: 1434-1948
    Keywords: Phosphenium cations ; Cation stabilities ; Electrophilicity ; Carbene homologues ; Computer Chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stabilities of low coordinated phosphorus cations can be expressed in the frame of the HSAB concept by the transferred charge density Δq(N) which a cation receives upon formation of a donor-acceptor adduct with a Lewis base N. This concept allows to differentiate between relative stabilities towards different reaction partners, and to compare the electrophilicities of phosphenium ions to those of isoelectronic carbenes and silylenes. An analysis of substituent influences on Δq(H) in cations [P(R)2]+suggests an increasing stabilizing power of substituents in the series R = Cl 〈 CH3 〈 OH, SH 〈 NH2. The same ordering was derived from isodesmic hydride transfer reactions. Interpretation of population analyses suggests that the individual substituent contributions to cation stabilities result from a balance between π-donation into the empty p(P) orbital and electrostatic stabilization by polar P-R σ-bonds. A further stabilizing effect, which is of similar magnitude as in isoelectronic carbenes or silylenes, may arise from cyclic π-conjugation between a diaminophosphenium fragment and an adjacent double bond. Substituent effects influence further the nature of the frontier orbitals of phosphenium ions, resulting in orbital sequences which resemble those of carbenes, allyl anions, or phospholides, respectively. The absence of frontier orbital related changes in reactivity patterns suggests that in all reactions, including metal complex formation, phosphenium ions behave as purely electrophilic rather than ambiphilic species.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 182
    Electronic Resource
    Electronic Resource
    The Aluminum-Nitrogen Bond in Monomeric Bis(amino)alanes: A Systematic Experimental Study of Bis(tetramethylpiperidino)alanes and Quantum Mechanical Calculations on the Model System (H2N)2AlY (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1095-1114 
    Details
    ISSN: 1434-1948
    Keywords: Aminoalanes ; Alanes ; Ab initio calculations ; 27Al-NMR spectroscopy ; Structure elucidation ; Substituent effects ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of metallated nucleophiles MIY [Y = OR, SR, NR2, PR2, AsR2, CR3, Si(SiMe3)3, R = organyl, H] with bis(2,2,6,6-tetramethylpiperidino)aluminum halides [tmp2AlX, (X = Cl, Br, I)] offer facile access to a variety of bis(amino)alanes of the type tmp2AlY. As indicated by 27Al-NMR spectroscopy, mass spectrometry and X-ray crystal structure determina-tions, all of these compounds are monomeric in the solid state, in solution, and in the gas phase. Even Al-E single bonds (E = Si, P, As etc.) that are not commonly encountered are stabilized by the supporting tmp fragments. The results of a systematic analysis of the bonding parameters determined for the tmp2AlY compounds, combined with a quantum mechanical study on model compounds (H2N)2AlY, not only reveal the presence of a highly polar Al-N bond, but at the same time rule out AlN-pp(π) bonding, in contrast to the situation in the analogous tmp2BY compounds. It is shown that the Al-N bond length depends on the acidic character of the protic species HY: the shorter d(Al-N), the less basic is Y.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 183
    Electronic Resource
    Electronic Resource
    Hydrolysis and Condensation Reactions of Transition Metal Alkoxides: Calorimetric Study and Evaluation of the Extent of Reaction (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1115-1127 
    Details
    ISSN: 1434-1948
    Keywords: Sol-gel process ; Polymers, inorganic ; Transition metal alkoxides ; 17O-NMR spectroscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behavior of titanium and zirconium alkoxides towards complexation and water addition is analyzed through water titration and calorimetric experiments. A simple model is presented, which allows evaluation of the mean hydrolysis and condensation constants, Kh and Kc, of both pure and complexed transition metal alkoxides in the sol state, through the analysis of consumed water versus initial hydrolysis ratio curves. These constants allow comparison of the extents of the hydrolysis and condensation reactions for sols obtained from several alkoxide precursors. The complexation ratio only affects the condensation constant Kc, whereas the hydrolysis constant Kh remains unchanged. Analysis of the Kh/Kc ratios has shown that in the sol state, silanol Si-OH groups are more stable than the Ti-OH or Zr-OH groups. Moreover, this study has shown that the proton concentration not only affects the kinetics, but also the final composition of the system. Calorimetric studies of the complexation and hydrolysis/condensation reactions have highlighted the role of coordination unsaturation of the transition metal alkoxides in the exothermicity of these reactions, clearly demonstrating that coordination unsaturation is the driving force behind the reactivity of these alkoxides towards nucleophilic species (e.g. water, complexing ligands, polar solvents).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 184
    Electronic Resource
    Electronic Resource
    Insertion Reactions into Palladium-Carbon Bonds of Complexes Containing Terdentate Nitrogen Ligands; Experimental and Ab initio MO Studies (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1129-1143 
    Details
    ISSN: 1434-1948
    Keywords: Insertion ; N ligands ; Terdentate ligands ; Rigid ligands ; Palladium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel methyl complexes [Pd(Me)(N-N-N)]X (N-N-N = flexible or rigid terdentate nitrogen ligand, X = Cl, SO3CF3, BAr′4) have been synthesized and fully characterized. All complexes readily underwent insertion of carbon monoxide resulting in the quantitative formation of complexes [Pd{C(O)Me}(N-N-N)]X [X = Cl (1d-6d), BAr′4 (1e-6e)]. Subsequently, complexes 2e-6e underwent quantitative insertion of norbornadiene, resulting in complexes [Pd{C7H8C(O)Me}(N-N-N)]BAr′4 (2f-6f). Unexpectedly, these complexes, including even those containing rigid terdentate nitrogen ligands, possess a structure in which the nitrogen ligand is coordinated in a bidentate fashion. A kinetic study of the reaction of norbornadiene with complexes 1e-6e revealed that the reactivity of complexes 1e-6e toward norbornadiene increases with increasing rigidity of the terdentate ligand, i.e. with increasing strain in the PdN3 moiety, which indicates that insertion very likely occurs via a mechanism involving nitrogen dissociation. This is fully supported by ab initio MO calculations on CO and ethylene insertion into carbon-palladium bonds of cationic model systems containing a rigid terdentate nitrogen ligand, which showed that the lowest-energy pathway for both insertion reactions consists of substitution of one of the distal nitrogen atoms of the rigid terdentate nitrogen ligand by the substrate, followed by a rate-determining migratory insertion of the substrate into the carbon-palladium bond.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 185
    Electronic Resource
    Electronic Resource
    Preparation, Structure and Reactivity of 2-Chloro-, 2-Fluoro- and 2-Iodo-2,3-dihydro-1H-1,3,2-diazaboroles (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1145-1152 
    Details
    ISSN: 1434-1948
    Keywords: Boron ; Diazaboroles ; Halogens ; Isocyanides ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of differently substituted 2-chloro-, 2-fluoro- and 2-iodo-2,3-dihydro-1H-1,3,2-diazaboroles have been prepared by various methods. 1,3-Di-tert-butyl-2-fluoro-2,3-dihydro-1H-1,3,2-diazaborole (3a), 1,3-di-tert-butyl-2-chloro-2,3-dihydro-1H-1,3,2-diazaborole (5a), 1,3-bis(2,6-dimethyl-phenyl)-2-chloro-2,3-dihydro-1H-1,3,2-diazaborole (5b), 2-chloro-4,5-dimethyl-1,3-dineopentyl-2,3-dihydro-1H-1,3,2-diazaborole (5c), and 1,3-di-tert-butyl-2-iodo-2,3-dihydro-1H-1,3,2-diazaborole (6a) were formed from the corresponding lithiated Z-1,2-diaminoethenes, by treatment with BF3·OEt2, BCl3, or BI3 in n-hexane. Compounds 3a, 5a, and 5b are also available by sodium amalgam reduction of the adduct (tBu)(BF3)N=CH-CH=N(BF3)(tBu) (2a), and the borolium salts [RNa=CH-CH=Nb(R)BCl2]X (Na-B) (4a: R = tBu, X = BCl4 and 4b: R = 2,6-Me2C6H2, X = Cl) respectively. The iodo derivative (2,6-Me2C6H2)-Na-CH=CH-Nb(2,6-Me2C6H2)BI (Na-B) (6b) was synthesized in a redox reaction between the 1,4-diazabutadiene 1b and BI3. The novel compounds were characterized by 1H-, 11B- and 13C-NMR spectroscopy, as well as by an X-ray structure analysis of 6b.Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2005/1998/98047_s.pdf or from the author.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 186
    Electronic Resource
    Electronic Resource
    Formation of a Constrained-Geometry Ziegler Catalyst System Containing a C1 Instead of the Usual Si1 Connection Between the Cyclopentadienyl and Amido Ligand Components (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1153-1162 
    Details
    ISSN: 1434-1948
    Keywords: “Constrained-geometry” Ziegler catalysts ; Cp/amido zirconium complex ; 6-Aminofulvene deprotonation ; Ethene polymerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 6-Amino-6-methylfulvene (4) is cleanly N-acylated by treatment with pivaloylchloride/triethylamine to give the fulvene (C5H4)=C(CH3)NHCOCMe3 (5c). Treatment of 4 with trimethylchlorosilane similarly yields the mono-N-silylated fulvene (C5H4)=C(CH3)NHSiMe3 (7). Both 5c and 7 are cleanly doubly deprotonated e.g. by treatment with LDA to give ligand systems [(C5H4)C(=CH2)NR]Li2 [8a (R = COCMe3) and 8b (R = SiMe3), respectively]. Their treatment with MCl4 · 2 THF (M = Ti, Zr) yield the spiro-metallocenes [(C5H4)C(=CH2)NR]2M (9, 10). Complex 10a (M = Zr, R = COCMe3) was characterized by X-ray diffraction. The reaction of 8a with (Et2N)2ZrCl2 in THF gives rise to the formation of [(C5H4)C(=CH2)NCOCMe3]Zr(NEt2)2 (11) (70 % isolated), and the reaction of 8b with (Et2N)2ZrCl2 yields [(C5H4)C(=CH2)NSiMe3]Zr(NEt2)2 (12) (76 % isolated). Treatment of complex 12 with an excess of methylalumoxane (MAO) in toluene solution results in the generation of an active homogeneous Ziegler catalyst for the polymerization of ethene. A comparison with the usually employed [(Me5C4)SiMe2NCMe3]ZrCl2/MAO “constrained-geometry” Ziegler catalyst system reveals a similar catalyst activity and performance of this novel type of a C1-bridged “constrained-geometry” catalyst as it is exemplified by the [(C5H4)C(=CH2)NSiMe3]ZrX2 (12)/MAO combination.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 187
    Electronic Resource
    Electronic Resource
    New P,N-Chelate Ligands Based on Pyridyl-Substituted Phosphaferrocenes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1163-1168 
    Details
    ISSN: 1434-1948
    Keywords: Chelates ; P,N ligands ; Phosphaferrocene ; Catalysis ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new pyridyl-substituted phosphaferrocene ligands 3 and 6 are prepared by addition of lithiated pyridine or α-picoline to 2-formyl-3,4-dimethylphosphaferrocene (1). The ligands 3 and 6 react with [Cp*RuCl]4 in THF to give the P,N-chelate complexes [Cp*RuCl·3] (9) and [Cp*RuCl·6] (10) with high diastereoselectivity. Addition of monodentate ligands like CO or PPh3 to the complexes leads by displacement of the Ru-bound pyridyl group to the respective carbonyl or phosphane complexes with monodentate P-coordinated phospha-ferrocene ligands. Reaction of the ligand 6 with [(C3H5)PdCl]2 and NH4PF6 gives the seven-membered chelate complex [(C3H5)Pd·6]PF6 (13) which was characterized by X-ray diffraction. The ligands 3 and 6 were tested in the palladium-catalyzed asymmetric alkylation of 1,3-diphenylallyl acetate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 188
    Electronic Resource
    Electronic Resource
    Coordination Modes of 2,5-Di(tert-butyl)pyrrolide - Crystal Structures of HPyr*, Pyr*H·thf, (thf)2LiPyr*, and [(Me3Si)3C-Zn]2(μ-Cl)(μ-Pyr*) (Pyr* = 2,5-tBu2NC4H2) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1175-1182 
    Details
    ISSN: 1434-1948
    Keywords: Hydrogen bonds ; Indium ; Lithium ; Nitrogen heterocycles ; Zinc ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The lithiation of 2,5-di(tert-butyl)pyrrole (1) yields bis(tetrahydrofuran)lithium 2,5-di(tert-butyl)pyrrolide (2), which is monomeric in solution as well as in the solid state. Due to the coordination number of three for the lithium atom, short Li-O and Li-N bond lengths of 193 pm are observed. The metathesis reaction of 2 with tris(trimethylsilyl)-methylzinc chloride (3) gives colorless bis[tris(trimethyl-silyl)methylzinc] chloride 2,5-di(tert-butyl)pyrrolide (4). The pyrrolide ligand and the chlorine atom bridge the zinc atoms. One of the zinc atoms is bonded to the nitrogen atom of the pyrrolide substituent, while the other bonds to the opposite C-C bond. At 215 pm, the Zn-N bond is very long compared to those in alkylzinc amides, whereas the Zn-C distances lie in the range of Zn-C bond lengths found between zinc and η5-bonded cyclopentadienide ligands. The molecular structures of 1 and of the low-melting THF adduct 1·thf show a similar 2,5-di(tert-butyl)pyrrole molecule, but in the latter case a weak N-H···O bond is observed (N-H 97 pm, O···H 199 pm).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 189
    Electronic Resource
    Electronic Resource
    On the Geometry of the Fulleride Dianion C602- in Crystalline Fullerides - Syntheses and Crystal Structures of [M(NH3)6]C60 · 6 NH3 (M = Mn2+, Cd2+) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1183-1186 
    Details
    ISSN: 1434-1948
    Keywords: Fullerides ; Crystal structure analysis ; Jahn-Teller effect ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fullerides [M(NH3)6]C60 (M = Mn2+, Cd2+) have been synthesized by ion exchange in liquid ammonia and analyzed by X-ray single-crystal diffraction. With both complex cations the C602- units are in fixed orientations, and their geometries have been determined with good accuracy. An inspection of the fulleride dianions with respect to geometric deformations in the title compounds and three further independent determinations has led to the conclusion that no significant static Jahn-Teller distortion is present.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 190
    Electronic Resource
    Electronic Resource
    Heterobimetallic and Mixed-Valence Chloro-Bridged Complexes with Orthometalated Rhodium(III) and Iridium(III) Fragments (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1187-1192 
    Details
    ISSN: 1434-1948
    Keywords: Iridium ; Rhodium ; Chloro-bridged complexes ; Heterobimetallic complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of heterobimetallic and mixed-valence complexes in which orthometalated [(ppy)2MCl] (M = Rh, Ir; ppy = 2-phenylpyridine anion) and [(bzq)2RhCl] (bzq = benzo[h]quinoline anion) fragments are linked via chloro-bridges with rhodium(I), iridium(I), palladium(II), and platinum(II) fragments is reported. These complexes are formed in nearly quantitative yields by metathesis reactions from the respective homodimeric compounds. The structures of [(ppy)2Rh(μ-Cl)2Rh(cod)] (cod = η4-1,5-cyclooctadiene) and [(ppy)2Rh(μ-Cl)2Pt(PBu3)-Cl] were determined by X-ray structure analyses.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 191
    Electronic Resource
    Electronic Resource
    Heterobimetallic d - f Metal Complexes as Potential Single-Source Precursors for MOCVD: Structure and Thermodynamic Study of the Sublimation of [Ni(salen)Ln(hfa)3], Ln = Y, Gd (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1169-1174 
    Details
    ISSN: 1434-1948
    Keywords: Heterobimetallic complexes ; Lanthanides ; Nickel ; Mass spectrometry ; Thermochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterobimetallic [Ni(salen)Ln(hfa)3] species [H2salen and Hhfa being N,N′-ethylenebis(salicylideneimine) and hexa-fluoroacetylacetone respectively], where Ni(salen) acts as a neutral chelating ligand towards LnIII, form a series of isostructural compounds for Ln = YIII and any lanthanideIII cation from La to Yb. They are also isostructural with some of the [Cu(salen)Ln(hfa)3] compounds. They sublime without decomposition under vacuum which makes them potential single-source precursors in MOCVD. Sublimation, thermal behaviour, pressure and composition of the vapour phase versus temperature have been studied for the yttrium derivative, by means of thermal analyses, and mass spectrometry using a Knudsen cell. The dissociation process [Ni(salen)Y(hfa)3] = Ni(salen) + Y(hfa)3 has been thermodynamically investigated. Information on the solid-state intermolecular interactions in relation with volatility was obtained through the crystal structure determination of the gadolinium derivative. A comparative structural study of [Ni(salen)Gd(hfa)3] and [Cu(saloph)Y(hfa)3], [H2saloph is N,N′-o-phenylenebis(salicylideneimine)], allows to under-stand why the latter is less volatile than the former despite similar molecular and solid-state structures.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 192
    Electronic Resource
    Electronic Resource
    Direct Evidence of Solvent-Peroxovanadium Clusters by Electrospray Ionization Mass Spectrometry (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1193-1197 
    Details
    ISSN: 1434-1948
    Keywords: Peroxo complexes ; Vanadium ; Mass spectrometry ; Ion-molecule reactions ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrospray Ionization Mass Spectrometry (ESI-MS) measurements and ab initio calculations on [OV(O2)(H2O)m-(CH3OH)n]+ (m,n: 0-4) peroxo cations have been carried out. This experimental technique allowed the direct observation of the above mentioned species for the first time. The results obtained clearly indicate that the exchange reactions between water and methanol molecules, within the coordination sphere of monoperoxo-vanadium complexes, is a conceivable and fast process.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 193
    Electronic Resource
    Electronic Resource
    4′-Nitro-2,2′:6′,2′′-terpyridine, 4′-Amino-2,2′:6′,2′′-terpyridine and Their Homo- and Heteroleptic Iron(II) and Ruthenium(II) Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1205-1207 
    Details
    ISSN: 1434-1948
    Keywords: Terpyridine ; Stille coupling reaction ; Microwave ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new ligands 4′-nitro-2,2′:6′,2′′-terpyridine and 4′-amino-2,2′:6′,2′′-terpyridine and their homoleptic and heteroleptic iron(II) and ruthenium(II) complexes have been prepared and the electrochemistry of the complexes has been investigated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 194
    Electronic Resource
    Electronic Resource
    Synthesis of Homo- and Hetero-Bimetallic Complexes Containing the Ni(C6F5)2 Moiety - Crystal Structure of [(C6F5)2Ni(μ-SPh)2Pd(dppe)] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1199-1204 
    Details
    ISSN: 1434-1948
    Keywords: Organometallic compounds ; Nickel complexes ; Crystal structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The compound cis-[Ni(C6F5)2(PhCN)2] has been used as the starting material for the preparation of the bimetallic complexes [(C6F5)2Ni(μ-X)2Ni(C6F5)2]2- (X = SCN, OCN, N3), [(C6F5)2Ni(μ-SCN)2Pd(C6F5)2]2-, [(C6F5)2Ni(μ-NCS)2Pd-(dppe)] [dppe = 1,2-bis(diphenylphosphanyl)ethane], and the trimetallic[(C6F5)2Ni(μ-NCS)2Pd(μ-SCN)2Ni(C6F5)2]2-. The mononuclear compounds [(C6F5)2NiLX] (L = PPh3, P(C6H4MeO-p)3; X = SCN, OCN) are obtained by reaction between [(C6F5)2Ni(&μ-X)2Ni-(C6F5)2]2- and L. The treatment of cis-[Ni(C6F5)2(PhCN)2] with [M(SAr)2(dppe)] leads to the formation of the arylthiolate complexes [(C6F5)2Ni(μ-SAr)2M(dppe)] (Ar = Ph, C6H4Me-p, C6H4NO2-p; M = Ni, Pd, Pt). The X-ray diffraction study of [(C6F5)2Ni(μ-SPh)2Pd(dppe)] shows that both metal atoms, Ni and Pd, are coordinated in a slightly distorted square-planar geometry and the μ-thiolato groups are in the syn conformation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 195
    Electronic Resource
    Electronic Resource
    Thermodynamic and Multinuclear NMR Study of Beryllium(II) Hydrolysis and Beryllium(II) Complex Formation with Oxalate, Malonate, and Succinate Anions in Aqueous Solution (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1209-1215 
    Details
    ISSN: 1434-1948
    Keywords: Beryllium(II) hydrolysis ; Beryllium(II) complexes ; Carboxylate ligands ; Thermodynamics of complex formation ; 9Be-NMR spectra ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydrolysis of beryllium(II) and its complexation by oxalate, malonate, and succinate in 0.5 mol dm-3 NaClO4 aqueous solution at 298 K has been studied by means of potentiometric (pH-metric), microcalorimetric, and multinuclear NMR-spectroscopic measurements. The protonation properties of the three ligands have also been investigated by potentiometry and microcalorimetry under the same experimental conditions. Thermodynamic results are consistent with a previously proposed chemical model for beryllium(II) hydrolysis, involving the species [Be2OH]3+, [Be3(OH)3]3+, [Be5(OH)6]4+, [Be6(OH)8]4+, and Be(OH)2. Complex formation of beryllium(II) with the dicarboxylate ligands is invariably promoted by favourable entropic contributions (ΔS° 〉 0), while the enthalpic terms are always unfavourable (ΔH° 〉 0). Malonate forms by far the most stable complexes owing to a more favourable (less endothermic) enthalpic contribution. These data reflect the fitting of the “bites” of the ligands with the stereochemically required tetrahedral coordination geometry about the metal ion, as well as the ligand preorganization.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 196
    Electronic Resource
    Electronic Resource
    Di- and Trinuclear Alkyne- and Vinylidenerhodium(I) Complexes Including the X-ray Crystal Structure of a Dendrimer-Like Rh3 Compound (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1217-1224 
    Details
    ISSN: 1434-1948
    Keywords: Rhodium ; Alkyne complexes ; Alkynyl(hydrido) complexes ; Vinylidene complexes ; Dendrimer-like structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dimer [RhClL2]2 (1; L = PiPr3) reacts with 1,3,5-C6H3(C≡CH)3 to give in the initial step the tris(alkyne)trirhodium compound 2, which rearranges in toluene at 60 °C to yield the isomeric tris(vinylidene) complex 3. Treatment of either 2 or 3 with pyridine affords the trinuclear tris(alkynyl)trihydridorhodium(III) complex 4. The trisilyl derivative 1,3,5-C6H3(C≡CSiMe3)3 reacts with 1 to form the mononuclear compound 5, in which only one of the C≡C bonds is coordinated to Rh. The diynes 1,3- and 1,2-C6H4(C≡CH)2 behave analogously to 1,3,5-C6H3(C≡CH)3 and upon treatment with 1 yield initially the bis(alkyne)dirhodium complexes 6 and 7 and subsequently the bis(vinylidene)dirhodium isomers 8 and 9. The reactions of 1,2-, 1,3-, and 1,4-C6H4(C≡CSiMe3)2 with 1 take a similar course and give the bis(alkyne) and bis(vinylidene) compounds 10-12 and 13-15, respectively. In the same way, the dinuclear bis(alkyne) and bis(vinylidene) complexes 16 and 17 have been prepared from 1 and the naphthalene derivative 1,5-C10H6(C≡CH)2. The molecular structures of 17 and of the dendrimer-like Rh3 compound 3 have been determined by X-ray crystallography.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 197
    Electronic Resource
    Electronic Resource
    Di-, Tri-, and Tetranuclear Cyclobutenylidene Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1225-1234 
    Details
    ISSN: 1434-1948
    Keywords: Vinylidene complexes ; Cyclobutenylidene complexes ; Bridging ligands ; Cycloadditions ; Cross-coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacarbonyl(dimethylvinylidene)chromium, [(CO)5Cr=C=CMe2] (1), reacts with the butadiynyl complexes [Cp(CO)2FeC≡CC≡CR] [2; R = SiMe3 (a), nBu (b), Ph (c)] and [Cp(CO)(PPh3)FeC≡CC≡CSiMe3] (3a) by regiospecific cycloaddition of the Cα≡Cβ bond of the butadiynyl complexes to the C=C bond of 1 to form the 1,3-heterobinuclear cyclobutenylidene complexes 4a-c and 5a with an alkynyl substituent at C-2 of the bridging ring. Desilylation of the 2-C≡CSiMe3 substituent in 4a and 5a with tetrabutylammonium fluoride affords the 2-C≡CH-substituted complexes 6 and 7. Complex 4a reacts with HNMe2 and HN(CH2)5 by substitution of NR2 for the 3-Fe(CO)2Cp fragment to form the corresponding 3-aminocyclobutenylidene complexes 10 and 11. Sequential reactions of 4a with [nBu4N]F and nBu3SnNEt2 give the trinuclear 2-C≡CSnnBu3-substituted complex 12. Coupling of 12 with C6H4I2-p yields the 2-C≡CC6H4I-p-substituted complex 13. Coupling of 7 with C6H4I2-p yields a mixture of the mono-coupling product 14 and the tetranuclear C≡C-C6H4-C≡C-bridged bis(cyclobutenylidene) complex 15. Coupling of 7 with trans-[(Et3P)2MCl2] in the presence of CuI/[Pd(PPh3)4] gives the trinuclear 2-C≡C-M(PEt3)2X-substituted complexes 16 (M = Pd, × = I) and 17 (M = Pt, × = Cl). The spectroscopic data as well as the results of the X-ray-structural analysis of 5a indicate strong electronic communication between the metal centers. In the solid state, 5a exhibits a “butterfly” conformation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 198
    Electronic Resource
    Electronic Resource
    Mesogenic Dinuclear Cyclopalladated Derivatives with Mixed Bridges - Crystal Structure of cis-[Bis({4,4′-di-n-butoxy}benzylideneaniline-C2,N)(μ-n-butylthiolato)(μ-chloro)dipalladium(II)] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1235-1241 
    Details
    ISSN: 1434-1948
    Keywords: Liquid crystals ; Palladium ; Metallomesogens ; Orthometallated imine ; Thiolate ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dinuclear cyclopalladated compounds [Pd(μ-Cl)Ln]2(2) [HLn = p-CnH2n+1OC6H4CH=NC6H4OCnH2n+1-p (n = 6, 8, and 10)] react with silver thiolates AgSRm (Rm = CmH2m+1, m = 6, 8, 10, and 18) to give dinuclear derivatives with mixed bridges [Pd2(μ-Cl)(μ-SRm)Ln2] (3). Treatment of derivatives 2 with silver acetate (Pd/AgOAc = 2:1) or treatment of [Pd(μ-OAc)Ln]2 (1) with thiols HSRm (Pd/thiol = 2:1) affords acetato-thiolato bridged complexes [Pd2(μ-OAc)(μ-SRm)Ln2] (4). In addition to their mesogenic behavior, the most interesting feature of these complexes is the cis disposition of the palladium-imine moieties, that can be inferred from their 1H-NMR spectra. The cis structure as well as the disposition of the bridges was confirmed by the X-ray diffraction study of 3 (n = m = 4).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 199
    Electronic Resource
    Electronic Resource
    Novel Nine-Membered Titanaheterocycles - Structure, ab initio Calculations, and Preparative Use towards the Selective Synthesis of Substituted Cyclopentanols (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1253-1262 
    Details
    ISSN: 1434-1948
    Keywords: Cyclizations ; Cross-coupling ; Ab initio calculations ; Titanium ; Metallacycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Cp2Ti(CO)2 (3) with two equivalents of α,β-unsaturated ketones 4 yield the novel titana-2,9-dioxacyclonona-3,7-dienes 5. Cross-coupling of 3 with two different ketones 4 and 6to give 7 can be achieved under certain reaction conditions. Hydrolysis of 5 or 7 may generate diketones 9, cyclopentanols 10/11, or cyclopentenes 12/13, depending on substituents and conditions. The X-ray crystal structure of 5a, the first nine-membered bis(η5-cyclopentadienyl)-substituted titanaheterocycle containing carbon, is presented. Ab initio calculations were performed for 5a and for titana-2-oxacyclopentene 1, a conceivable intermediate in the coupling reaction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 200
    Electronic Resource
    Electronic Resource
    Syntheses, Structures, and Spectroscopic Properties of cis,cis-and trans,cis-[Ru(I)(Me)(CO)2(α-diimine)] Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1243-1251 
    Details
    ISSN: 1434-1948
    Keywords: Ruthenium ; α-Diimine ligand ; Carbonylmetal compounds ; Isomers ; X-ray structure ; Resonance Raman spectra ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses, structures, and spectroscopic properties are reported for trans,cis and cis,cisisomers of [Ru(I)(Me)(CO)2(α-diimine)] [α-diimine = N,N′-diisopropyl-1,4-diazabutadiene (iPr-DAB), pyridine-2-carbaldehyde N-isopropylimine (iPr-PyCa), 4,4′-dimethyl-2,2′-bipyridine (dmb)] which differ in their photochemical behaviour. The structures of trans,cis- and cis,cis-[Ru(I)(Me)(CO)2(iPr-DAB)] have been determined by a single-crystal X-ray diffraction study. The crystals of both isomers are monoclinic and belong to the same P21/n space group with Z = 4. Refinement converged to R = 0.043 for the trans,cis isomer and to R = 0.065 for the cis,cisisomer. Both complexes have a distorted octahedral geometry, in the cis,cisisomer the methyl ligand is located in an equatorial, the iodide in an axial position. According to the 1H- and 13C-NMR and resonance Raman spectra the imine groups of the iPr-DAB ligand are inequivalent in the cis,cis isomer. The absorption spectra vary with the α-diimine, not so much with the isomeric structure of the complex. Both isomers possess two visible absorption bands, which, according to the resonance Raman spectra, belong to charge transfer transitions from mixed metal-halide orbitals to the α-diimine. The resonance Raman spectra show that this charge transfer excitation is accompanied, for both isomers, with an angular distortion of the methyl ligand. These spectral data show that the difference in photochemical behaviour of the two isomers is not due to a change in the excited state character.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...