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  • LUNAR AND PLANETARY EXPLORATION  (928)
  • Inorganic Chemistry  (727)
  • Animals  (466)
  • 1995-1999
  • 1990-1994  (2,121)
  • 1950-1954
  • 1930-1934
  • 1993  (2,121)
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  • 1995-1999
  • 1990-1994  (2,121)
  • 1950-1954
  • 1930-1934
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  • 101
    Electronic Resource
    Electronic Resource
    Enzym-katalysierte Reaktionen, 15. Darstellung von (R)1-2-(Sulfonyloxy)nitrilen und ihre Reaktionen mit Acetaten  -  Konfigurationsumkehr optisch aktiver Cyanhydrine[2] (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 779-786 
    Details
    ISSN: 0009-2940
    Keywords: (R)1-2-(Sulfonyloxy)nitriles, synthesis of, reaction with alkali acetates ; (S)1-Cyanohydrin acetates, synthesis of ; Nitriles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enzyme-Catalyzed Reactions, 15[1]. - Preparation of (R)1-2-(Sulfonyloxy)nitriles and Their Reactions with Acetates - Inversion of the Configuration of Optically Active Cyanohydrins2-(Sulfonyloxy)nitriles (R)-6, 7, 8 are obtained in high optical purity from the respective cyanohydrins (R)-2 by sulfonylation with methanesulfonyl chloride (3), toluenesulfonyl chloride (4), and trifluoromethanesulfonic anhydride (5), respectively. In contrast to the aliphatic (sulfonyloxy)nitriles (R)-6, 7, 8a - e, the benzylic-type mandelic acid derivatives (R)-7,8í are unstable at higher temperature. The 2-(sulfonyloxy)nitriles (R)1- 6, 7, 8a - e react at room temperature with alkali acetates in a typical SN2 manner to give the cyanohydrin acetates (S)-9 in high optical purity. Under these reaction conditions, however, the mandelic-type compounds (R)-7, 8í partly racemize and decompose. By hydrolysis of the acetates (S)-9, (S)1-cyanohydrins (S)-2 of aliphatic aldehydes are easily available.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260332
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  • 102
    Electronic Resource
    Electronic Resource
    Photoinduced Electron Transfer in Porphyrin-Quinone Cyclophanes, 8 Conformational Mobility and Crystal Structures of Porphyrin-Quinone Cyclophanes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 811-821 
    Details
    ISSN: 0009-2940
    Keywords: Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Porphyrin cyclophanes, conformational mobility of, crystal structures of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to correlate photoinduced electron-transfer in porphyrin-quinone cyclophanes to specific molecular conformations, the internal mobility of single-and double-bridged porphyrin-quinone cyclophanes was studied by low-temperature 1H-NMR measurements. The dynamic processes observed are discussed in terms of N-H/N tautomerisation, of the rotation of the rings in the bridges, and of a specific “swinging bridge” process back and forth between two equivalent unsymmetrical conformations with a tilted orientation of the porphyrin and quinone ring planes. For comparison with the conformational situation in solution the results of X-ray structure analyses of 3(X=OMe) and 6, as representative examples of single-bridged quinone-porphyrin cyclophanes, and of the corresponding tetramethoxybenzene-bridged octamethylporphyrin cyclophane 4(X=OMe) are reported and discussed. In contrast to the previously solved crystal structure of the quinone-porphyrin-quinone cyclophane 1(X=H), all three X-ray structure analyses of the single-bridged porphyrin cyclophanes proved the existence of unsymmetrical, tilted-plane structures similar to those discussed as the stable conformations in the “swinging bridge” process.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260336
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  • 103
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260401
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  • 104
    Electronic Resource
    Electronic Resource
    Synthesis and Crystal Structure of the First “1,2-Diphospha[4]radialene” (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 845-847 
    Details
    ISSN: 0009-2940
    Keywords: Hetero[4]radialene ; 1,2-Diphosphetane ; Butadiene, 2,3-bis(chlorophosphanyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Diphosphetane 4, the first “1,2-diphospha[4]radialene”, has been prepared in 83% yield by the reductive coupling reaction of 2,3-bis(chloroisopropylphosphanyl)butadiene 3a with lithium in THF. The X-ray crystal structure of 4 was determined, and it shows that 4 is a highly strained 1,2-diphosphetane.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260340
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  • 105
    Electronic Resource
    Electronic Resource
    Neue zwitterionische λ51-Spirosilicate: Synthesen, Einkristall-Röntgenstrukturanalysen und Festkörper-NMR-Untersuchungen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 851-861 
    Details
    ISSN: 0009-2940
    Keywords: Spirosilicates, zwitterionic ; Silicon, pentacoordinate ; Bond cleavage, Si - C ; Solid-state NMR, 29Si and 15N ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Zwitterionic λ51-Spirosilicates: Syntheses, Single-Crystal X-Ray Structure Analyses, and Solid-State NMR StudiesThe zwitterionic spirocyclic λ51-silicates bis[3,4,5,6-tetrabromo-1,2-benzenediolato(2-)][2-(pyrrolidinio)ethyl]silicate (5; and its monohydrate 5 · H2O) and bis[1,2-benzenediolato(2-)]1-[(dimethylammonio)methyl]silicate (6) were synthesized by various methods including Si - C bond cleavage reactions. The crystal structures of 5, 5·H2O, and 6 were investigated by X-ray diffarction. Furthermore, 5, 5·H2O, 6, and the related zwitterionic λ51-spirosilicates 1·1/4 CH3CN, 2·CH3CN, 3·CH3CN, and 4 were characterized by solid-state NMR spectroscopy (29Si and 15N CP/MAS). The pentacoordinate silicon atoms of 5, 5·H2O (two cystallographically independent zwitterions and two crystallographically independent water molecules), and 6 (two crystallographically independent zwitterions) are surrounded by four oxygen atoms and one carbon atom. The coordination polyhedrons around the silicon atoms of 5 and 6 can be described as distorted (5) or nearly ideal (6) trigonal bipyramids, the carbon atoms being in equatorial positions. 5 forms intramolecular and 6 intermolecular (→ for-mation of dimeric units) N - H…O hydrogen bonds. The co-ordination polyhedrons around the two crystallographically independent silicon atoms of 5·H2O can be described as a nearly ideal and slightly distorted square pyramid, respectively, the carbon atoms being in the apical positions. In the crystal lattice of 5·H2O, intermolecular N - H…O O - H…O hydrogen bonds between the zwitterions and water molecules are observed. The results obtained by X-ray diffraction and solid-state NMR spectroscopy are consistent for each compound studied.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260402
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  • 106
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    Beiträge zur Chemie des Bors, 216. Über die Komplexbildung von 1,3,2,4-Diphosphadiboretanen mit Pentacarbonylchrom sowie über die Darstellung und Reaktivität von Borylidenphosphan-Komplexen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 875-887 
    Details
    ISSN: 0009-2940
    Keywords: 1,3,2,4-Diphosphadiboretanes, 2,4-bis(dialkylamino)- ; Boranes, (dialkylamino)bis(alkylphosphanyl)- ; Chromium, pentacarbonyl[2,3-bis(dialkylamino)1-1,3,2,4-diphosphadiboretane] complexes ; Chromium, pentacarbonyl[(2,2,6,6-tetramethylpiperidino)phosphane-P]- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contributions to the Chemistry of Boron, 216[1]. - On the Complex Formation of 1,3,2,4-Diphosphadiboretanes with Pentacarbonylchromium and the Preparation and Reactivity of Borylidenephosphane Complexes2,4-Bis(dialkylamino)1-1,3,2,4-diphosphadiboretanes (R2NBP-CMe3)2 with sterically undemanding amino substituents are prepared together with the corresponding bis(phosphanyl)1-boranes R2NB(PHCMe3)2 by the reaction of R2NBCl2 with Li-P(H)CMe3. Complexes of 1,3,2,4-diphosphadiboretanes with one or two pentacarbonylchromium fragments were obtained by the reaction of the ligands with Cr(CO)5·THF or Cr(CO)5·NMe3. If substituents are sterically demanding, cycloreversion is observed with formation of [(aminoborylidene)1-phosphanyl-P]pentacarbonylchromium compounds tmpB=PR[Cr(CO)5] (10, 29) with an allene-like structure. Complex 29 may also be prepared by HCl elimination from tmp-B(Cl)-P(H)CMe3[Cr(CO)5] (34) with lithium diisopropylamide. This reaction can by reversed be the addition of HCl. The diphosphadiboretane 11 reacts with HCl, ethanol, and secondary amines with cleavage of all BP bonds. The X-ray structures of complexes (Et2NB - PCMe3)2[Cr(CO)5]2 (23) and (iPr2NB - PCEt3)2 [Cr(CO)5] (25) as well as of the diphosphadi-boretanes (Me2NB - PCMe3)2 (11) and (iPr2NB - PCEt3)2 (24) are presented. The intra ring angles of 23 remain almost unchanged upon complexation. In contrast, the B2P2 ring of 25 is slightly folded and its noncoordinated P atom approaches a planar environment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260405
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  • 107
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    Metallorganische Verbindungen der Lanthanoide, 73. Synthese und Struktur neuer Monocyclooctatetraenyl-Komplexe von Yttrium, Terbium und LutetiumHerrn Professor Ulrich Wannagat zum 70. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 907-912 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienyl complexes ; Cyclooctatetraenyl complexes ; Yttrium compounds ; Terbium compounds ; Lutetium compounds ; Lanthanoides, organo-, alkoxides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Compounds of the Lanthanoids, 73[1]. - Synthesis and Structure of New Monocyclooctatetraenyl Complexes of Yttrium, Terbium, and Lutetium[(C8H8)Ln(μ1-Cl)(THF)]2 (Ln=Y, Lu) react with NaOR (R=Ph, C6H3Me2-2,6) to give the dinuclear cyclooctatetraenyl rare earth alkoxides [(C8H8)Ln(μ1-OR)(THF)]2 [R=Ph, Ln=Y (1a), Lu (1b); R=C6H3Me2-2,6, Ln=Y (2a), Lu (2b)]. The reactions of [(C8H8)Ln(μ1-Cl)(THF)]2 with LiOC(tBu)3, NaOSiPh3, and NaC5H3tBu2 result in the formation of (C8H8)LnOC(tBu)3(THF) [Ln=Y (3a), Lu (3b)], (C8H8)LnOSiPh3(THF) [Ln=Y (4a), Lu (4b)], and (C8H8)Tb(C5H3tBu2) (5), respectively. Treatment of (C8H8)Y(C5Me5) with acetylacetone yields (C5Me5)Y(acac)2 (6). The 1H-and 13C-NMR and mass spectra of the new compounds as well as the X-ray crystal structures of 1a and 5 are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260409
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  • 108
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    Synthese und Reaktionen von (η51-Pentamethylcyclopentadienyl)1- und (η51-Ethyltetramethylcyclopentadienyl)titantrifluorid (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 913-919 
    Details
    ISSN: 0009-2940
    Keywords: Organometallic fluorides ; Titanium ; π1-Complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Reactions of (η51-Pentamethylcyclopentadienyl)1- and (η51-Ethyltetramethylcyclopentadienyl)titanium Trifluoride[1]Compound Cp*TiCl3 (1, Cp*=η51-Me5C5) reacts with an excess of AsF3 to yield the crystalline complex [Cp*TiF3]2·2 AsF3 (2). AsF3 can be removed from 2 in vacuo to give Cp*TiF3 (3). Complex (η51-EtMe4C5)TiCl3 (4) is converted by an excess of AsF3 to (η51-EtMe4C5)TiF3 (5). Compound 3 reacts with a lithium 1,3-diketonate to form the hexacoordinated complex (6) and with a lithium benzamidinate to yield pentacoordinated Cp*TiF2[(Me3SiN)2 C-C6H4OMe-(4)] (7): The reaction of 3 with Ph3PNSiMe3 and C2H2(Ph2PNSiMe3)2 leads to Cp*TiF2NPPh3 (8) and (Cp*TiF2NPPh2)2C2H2 (9), respectively. X-Ray structure analyses of compounds 2 and 5-9 have been performed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260410
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  • 109
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    Tetraalkylhydrido-und Tetraalkylmethyldialuminat(5) mit Aluminium - Aluminium-Bindung: [R2Al - AlXR2]- {R=CH(SiMe3)2; X=H, Me} (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 941-945 
    Details
    ISSN: 0009-2940
    Keywords: Aluminium - aluminium bond ; Dialuminate(5) with three-and fourfold coordinated aluminium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetraalkylhydrido-and Tetraalkylmethyldialuminate(5) with Aluminium - Aluminium Bond: [R2Al - AlXR2]- {R=CH(SiMe3)2; X=H, Me}Tetrakis[bis(trimethylsilyl)methyl]dialuminium(4) (1) with an aluminium - aluminium bond reacts with tert1-butyllithium in the presence of the chelating tetramethylethylenediamine (TMEDA) to give a hydridodialuminate(5) 2 [R2Al - AlHR2]- {R=CH(SiMe3)2} by β1-elimination and addition of the hydride anion to one aluminium atom. By treatment of 1 with methyllithium a similar product is formed containing a methyl group bound to aluminium: [R2A1 - AlMeR2]- 3. As shown by crystal structure determination the aluminium - aluminium bond of both molecules is not bridged. Instead, the compounds contain a saturated, four-coordinated aluminium neighbouring an unsaturated, threefold coordinated aluminium atom. While in the hydrogen compound 2 the aluminium - aluminium bond length [266.7(3) pm] remains unaffected in comparison to the neutral starting compound 1, it is lengthened in the methyl derivative 3 by 9 pm to 275.2(3) pm probably due to the higher sterical demand of the methyl group.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260414
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  • 110
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    Einkernige Nickel-Thiolato-Komplexe mit Nickel-Zentren in unterschiedlichen Oxidationszuständen: Molekularer Aufbau von [Ni(SC6H4O)2]2- und [Ni(SC6H4O)2]Herrn Professor Dietrich Mootz zum 60. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 951-953 
    Details
    ISSN: 0009-2940
    Keywords: Thiolato ligands ; Nickel complexes ; Hydrogenase models ; Bioinorganic chemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mononuclear Nickel Thiolate Complexes Containing Nickel Sites in Different Oxidation States: Molecular Definition of [Ni(SC6H4O)2]2- and [Ni(SC6H4O)2]Herrn Professor Dietrich Mootz zum 60. Geburtstag gewidmet.A solution of NiCl2·6 H2O in EtOH/H2O reacts with nBu3N and o1-mercaptophenol to form [nBu3NH]2[Ni(SC6H4O)2]·EtOH (2) containing the nickel(II) complex [Ni(SC6H4O)2]2- (1). The molecular structures of 1 and its oxidation product, [Ni(SC6H4O)2]- (3), have been determined by X-ray diffraction. With respect to the chemical as well as electrochemical properties of the nickel sites of various hydrogenases, 3 is the first relevant model complex of coordination number four whose structural properties have been determined in different oxidation states.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260416
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  • 111
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    Maßgeschneiderte Wirtverbindung für Piperazin und verwandte Amine (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1003-1009 
    Details
    ISSN: 0009-2940
    Keywords: Diamine ; Host-guest chemistry ; Macrocycle ; Supramolecular chemistry ; Receptor molecule, synthetic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tailor-Made Host for Piperazine and Related AminesThe 38-membered bis-catechol 4b is obtained by cyclisation of the diacyl dichloride 3c with the diamine 2b in 45% yield, whereas a 68-membered octalactam 7 is formed under similar conditions from 5 and 1b. Bis-catechol 4b is a selective host compound for piperazine (8) and the structurally related diamine 9. Association constants for the 1:1 complexes have been measured by 1H-NMR titration experiments. A nucleobase guest (pterine, 24) was extracted into a hydrochloric acid phase by complex formation with the host 4b. The results are compared with solubility and transport experiments obtained by use of analogous macrobicyclic tris-catechol hosts.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260421
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  • 112
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    AM1 and X-ray Studies of the Structures and Isomerization Reactions of Indigo Dyes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1015-1021 
    Details
    ISSN: 0009-2940
    Keywords: Indigo ; Calculations, AM1 ; cis/trans Isomerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: AM1-SCF and AM1-SDCI calculations have been carried out for indigo and three conformers of N,N′1-diacetylindigo in their cis and trans configurations. The molecular structure of trans- N,N′1-diacetylindigo was determined by X-ray diffraction. The calculated ground-state data obtained within the SCF approximation (relative energies, structural parameters) are in excellent agreement with the corresponding experimental values. Potential energy curves (PEC) for the isomerization reaction cis/trans in several electronic states were obtained from AM1-SDCI calculations. For N,N′1-diacetylindigo the ground state PEC has a maximum at a torsion angle about the central C—C bond of 90°, whereas the S1- and T11-state PEC's show minima at the corresponding geometry. For indigo itself significant barriers to the photoisomerization in the S1- and T11-excited states are predicted because of increased NH…OC hydrogen bonding. The results provide an explanation for the phototropic behaviour of N,N′1-diacetylindigo and the photostability of indigo. The calculated enthalpies of activation for the isomerization process cis → trans in the ground state compare well with available experimental data, thus rendering feasible the prediction of the thermal stability of cis isomers not yet synthesized.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260423
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  • 113
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    Substituenteneffekte auf die C—C-Bindungsstärke, 13. Kinetische und thermodynamische Stabilität von α1-alkylierten α1-Amino-carbonsäureestern - Stabilisierungsenergie von α1-Amino-α1-(ethoxycarbonyl)alkyl-Radikalen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1031-1038 
    Details
    ISSN: 0009-2940
    Keywords: C—C Bond cleavage, kinetics of ; Heat of formation ; Radicals, stability of ; Capto-dative effect ; Geminal substituents, energetic interaction of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects on the Strength of C—C Bonds, 13[1]. - Kinetic and Thermodynamic Stability of α1-alkylated α1-Amino Acid Esters - Energy of Stabilization of α1-Amino-α1-(ethoxycarbonyl)alkyl RadicalsThermolytic cleavage of 1a-c and 2a-c into radicals in solution are clean first-order processes. The activation parameters for C—C bond homolysis were determined. Compared with the corresponding data for hydrocarbons of equal strain a decrease of bond strength of 14.4 kcal/mol results by the combined interaction of the amino and the ethoxycarbonyl substituents. The heat of formation of 5 was determined by combustion calorimetry [δHco (1)=- 1207.75 ± 0.20 kcal/mol] combined with the heat of vaporization (δHvo=13.31 ± 0.10 kcal/mol). Compared with the additive behaviour of group increments the resulting heat of formation (δHfo (g)=- 112.02 ± 0.24 kcal/mol] suggests a synergetic, geminal destabilization of Hsyn=1.9 ± 1.4 kcal/mol. Combination of the kinetic data of bond homolysis of 1a-c and 2a-c with the synergetic ground-state destabilization leads to a synergetic, capto-dative radical stabilization of Hsyn (rad)=6.7 kcal/mol.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260425
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  • 114
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    Zur Energiedelle des orthogonalen Trimethylenmethans. - 1-Methylen-2-phenylcyclopropan-Thermolyse (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2717-2725 
    Details
    ISSN: 0009-2940
    Keywords: Diradicals ; Oxygen trapping ; Energy well ; Heat of formation ; Heat of hydrogenation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Energy Well of the Orthogonal Trimethylenemethane. - 1-Methylene-2-phenylcyclopropane ThermolysisFrom the heat of hydrogenation of 5, the activation enthalpy for the racemization of the title compound, and the oxygen dependance of the trapping rate of the intermediate diradical 8 the energy profile for the degenerate methylene-cyclopropane rearrangement can be constructed, which leads to heats of formation for the triplet and singlet state of the diradical 8 of ΔHf0 · 93.9 and 95.6 kcal mol-1, respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261222
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  • 115
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    Synthese optisch aktiver 2-Siloxycyclopropancarbonsäureester durch asymmetrische Katalyse, II[1]. Einfluß der Silylenolether-Struktur auf die enantioselektive Cyclopropanierung mit Diazoessigsäure-methylester (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2727-2732 
    Details
    ISSN: 0009-2940
    Keywords: 2-Siloxycyclopropanecarboxylates ; Silyl enol ethers ; [2 + 1] Cycloaddition ; Asymmetric catalysis ; (Schiff base)copper complexes, chiral ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Optically Active Siloxycyclopropanes by Asymmetric Catalysis, II[1]. - Influence of the Silyl Enol Ether Structure on the Enantioselective Cyclopropanation with Methyl DiazoacetateOn the basis of reactions of (Z)-1-phenyl-1-(trimethylsiloxy)-1-propene (1a) with methyl diazoacetate (2) in the presence of different chiral (Schiff base) copper catalysts 4-Cu we extended our study to the silyl enol ethers 1b-1j. The highest enantiomeric excesses were obtained in most cases with catalyst 4b-Cu. Whereas cyclopropanations of 1-aryl- and 1-alkenyl-substituted silyl enol ethers 1b-1h gave moderate to good enantioselectivities (up to 80%ee), alkyl-substituted olefins 1i and 1j provided less satisfactory results. By deprotonation and alkylation of 3c, 3h, and 3i it could be established that for these cyclopropanes the predominating absolute configuration of cis- and trans-cyclopropanes is equal at C-1, but consequently opposite at C-2. The influence of the silyl enol ether structure on the enantioselectivities achieved is briefly discussed.
    Additional Material: 4 Tab.
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    NMR Spectroscopy of Organolithium Compounds, XV[1]. Two-Dimensional 6Li,1H-NMR Shift Correlation by Multiple Quantum Spectroscopy and Polarization Transfer: New Tools for Structural Research in the Field of Organolithium Compounds (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2747-2751 
    Details
    ISSN: 0009-2940
    Keywords: Polylithium compounds ; NMR, 6Li ; Shift correlation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sizable scalar 6Li,1H spin-spin coupling constants have been observed for the new dilithio compound (Z)-2-lithio-1-(o-lithiophenyl)ethene (3) which allow an assignment of the two non-equivalent 6Li resonance signals measured for the dimer of 3. Two-dimensional 6Li,1H shift correlation experiments based on multiple quantum spectroscopy as well as on polarization transfer are introduced as new tools for structural research in the field of organolithium compounds.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261226
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    Stereoselektive Synthese von 3-substituierten Cyclobutanolen und Folgeprodukten (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2759-2763 
    Details
    ISSN: 0009-2940
    Keywords: Dichloroketene ; Stereoselective ketone reduction ; Mitsunobu reaction ; Cyclobutyl bromides ; Cross-coupling reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Synthesis of 3-Substituted Cyclobutanols and Products Derived Therefrom3-Substituted cyclobutanones 2 are prepared by alkene/dichloroketene cycloadditions and subsequent dehalogenation. Reduction with LiAlH(OtBu)3 furnishes cis-cyclobutanols 3 in 95-100% selectivity. Mitsunobu inversion turned out to be the only practical method to get trans isomers 4 in high selectivity. A stereoselective cyclobutanol→bromocyclobutane conversion could be achieved only by a modified Mitsunobu reaction. Cross coupling between zinc derivatives of bromocyclobutanes 9 and aromatic bromides is not stereoselective.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931261228
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    4H,5H-Benzo[1,2-c;3,4-c′]bis[1,2,5]thiadiazole-4,5-dione (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2767-2769 
    Details
    ISSN: 0009-2940
    Keywords: 4H,5H-Benzo[1,2-c;3,4-c′]bis[1,2,5]thiadiazole-4,5-dione ; 5,6-Dihydroxybenzenetetramine ; 5,6-Dimethoxybenzenetetramine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4H,5H-Benzo[1,2-c;3,4-c′]bis[1,2,5]thiadiazole-4,5-dione (2) was prepared by oxidation of 4-bromobenzobis[1,2,5]thiadiazole (3d) with nitric acid and subsequently converted into 5,6-dihydroxybenzenetetramine dihydrochloride (10) and the dimethoxy derivative 13. Treatment of the 4-hydroxy derivative 3a with chromium(VI) reagents led to cleavage of the benzene ring, giving dicarboxylic acid 4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261230
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    Metallated Bicyclo[3.2.2]nona-2,6,8-trienes, Their Rearrangement to Barbaralanes, and a Short Synthesis of the Bicyclo[3.2.2]nona-2,6,8-trien-4-yl AnionDedicated to Professor Heinrich Nöth on the occasion of his 65th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1283-1290 
    Details
    ISSN: 0009-2940
    Keywords: Deprotonation ; 1,5-Homodienyl shift ; Bicyclo[3.2.2]nona-2,6,8-trienes ; Tricyclo[3.2.2.02,4]nona-6,8-dienes ; Barbaralanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five different anions are formed when bicyclo[3.2.2]nona-2,6,8-triene (1a) is deprotonated: the 6- and 7-yl anions when using tBuLi/TMEDA, the 4,6- and 4,7-diyl dianions when using nBuLi/tBuOK, and the 4-yl anion (1-) after quenching the dianions with THF. Reaction of the anions with Me3SnCl gives the 6-, 7-, and 4-monostannylated bicyclo[3.2.2]nona-2,6,8-trienes 1b, 1c, and 1d as well as the exo-4,7-, endo-4,6-, and endo-4,7-distannylated bicyclo[3.2.2]nona-2,6,8-trienes 1e, 1f, and 1g, respectively. Reaction of 1- with Me3SiCl and Me3PbCl leads to the corresponding 4-silyl derivative 1h and its plumbyl analogue 1i. Inversely, cleavage of 1d with MeLi allows to generate 1- under particularly mild conditions. The metallation of tricyclo[3.2.2.02,4]nona-6,8-diene (3a), which was tested for an alternative route to 1-, gives two stannyl derivatives 3b and 3c which are substituted in the vinylic positions. - On heating 1d and 1i rearrange to yield 9-trimethylstannylbarbaralane (2d) and its plumbyl analogue 2i quantitatively. The reactivity decreases on passing from 1i to 1d whereas 1h does not react. Mercury and zinc derivatives of 1- are so labile that only dibarbaralylmercury (2j) and -zinc (2k) are observed by NMR spectroscopy. The title rearrangement proceeds by a 1,5-homodienyl metallatropic shift which involves an endo1-type transition structure. - The new compounds 1b - i, 2d, 2i, 3b and 3c are characterized with emphasis on the NMR data including 1H, 13C, 119Sn, 207Pb signal shifts and various heteronuclear couplings.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260604
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    Methylenphosphanyl-Komplexe von Chrom, Molybdän, Wolfram, Eisen und Nickel: Synthese und ReaktionenHerrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1299-1309 
    Details
    ISSN: 0009-2940
    Keywords: Methylenephosphanyl complexes ; Phosphenium complexes ; Phosphavinylidene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methylenephosphanyl Complexes of Chromium, Molybdenum, Tungsten, Iron and Nickel - Synthesis and ReactivityHerrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet.The reaction of the functionalized P/C double bond systems X - P=C(R)SiMe3 [R=SiMe3 and X=Cl (1a), Cp* (5a) or R=Ph and X=Br (1b), Cp* (5b)] with alkali carbonylmetallates or carbonyl complexes of group 6, 8, and 10 metals leads to the formation of the transition metal-substituted phosphaalkenes [{M} - P=C(R)SiMe3 3a - j and 4a - i], in which the P - C fragment acts as a one-electron donor. Depending on the nucleophilicity of the transition metal anion used, but also on the methylene carbon substituents [1a: (SiMe3)2: 1b: (Ph)1-SiMe3], a different stability of the (methylenephosphanyl)1-metal complexes is observed, which results in a broad spectrum of reactivities. As demonstrated by the reactions of the (methylenephosphanyl)metal complexes with sulfonic acid derivatives (10a - c), diverse transition metal complexes (11a - c), as well as chalcogenes (14a - c, 15), a change in the reactivity is observed, indicating a transition from an olefinic to a carbenic character of the methylenephosphane. In comparison to the phenyl-substituted derivatives 4a - i the bis(trimethyl)1-substituted species 3a - j exhibit an increased reactivity. This is reflected in the easy decarbonylation of 3a - d to the phosphavinylidene complexes 12a - d.
    Additional Material: 3 Ill.
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    Synthesis, X-Ray Structure and Complexation Behavior of the New Tripodal Phosphane Ligand cis, cis-1,3,5-Tris[(diphenylphosphanyl)methyl]1-1,3,5-trimethylcyclohexane (tdppmtmcy). Crystal Structure of Ir(tdppmtmcy)(CO)Cl (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1341-1346 
    Details
    ISSN: 0009-2940
    Keywords: Phosphane ligand, tripodal ; Iridium complex ; C—H activation, intramolecular ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The introduction of three methyl groups into the ipso positions of the cyclohexane ring in cis,cis-1,3,5-tris[diphenylphosphanyl)methyl]cyclohexane (tdppmcy) (1) leads to the new tripodal phosphane ligand cis,cis-1,3,5-tris(diphenylphosphanyl)methyl]1-1,3,5-trimethylcyclohexane (tdppmtmcy) (5). The dynamic behavior is studied by variable-temperature NMR spectroscopy and compared with the structure (X-ray analysis) in the solid state. Treatment of 5 with Ir(PPh3)2(CO)Cl gives 6 where the two PPh3 groups are replaced by two (diphenylphosphanyl)methyl groups of the ligand 5. In addition, an intramolecular C—H metalation takes place resulting in the oxidative addition of a ring methylene C—H bond to the metal. The X-ray structure of 6 is determined.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260612
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    Eigenschaften von Chalkogen-Chalkogen-Bindungen, XVII. Di-und Trisulfane mit sterisch anspruchsvollen Alkyl-Substituenten: Das erste trans1-Dialkyldisulfan (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1355-1359 
    Details
    ISSN: 0009-2940
    Keywords: Disulfanes ; Trisulfanes ; Bond conformations, S—S ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Properties of Chalcogen-Chalcogen Bonds, XVII[1]. - Di-and Trisulfanes with Sterically Congested Alkyl Substituents: The First trans1-DialkyldisulfaneBis[tris(trimethylsilyl)methyl]trisulfane (1) is obtained from tris(trimethylsilyl)methyllithium and sulfur with subsequent oxidation by oxygen or from tris(trimethylsily)methanethiol with sulfur dichloride. The solid trisulfane contains a transoid (helical) C—S-S—S-C backbone without severe distortion from steric strain. Desulfuration of the byproduct bis[tris(trimethylsilyl)methyl]tetrasulfane (2) with mercury provides 1, but further desulfuration of 1 to bis[tris(trimethylsilyl)1-methyl]disulfane (3) has not been achieved. 3 was isolated after oxidation of lithium tris(trimethylsilyl)methanethiolate with bromine. 3 contains a trans1-C—S-S—C moiety with an unusually long S—S bond (210-211 pm). The less crowded bis(triphenylmethyl)disulfane (4) contains a “normal” C—S-S—C moiety with anticlinal conformation (torsion angle - 110°).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260614
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    Organosubstituierte 1,1′-Spirobisilole und 1,1′-Spirobigermole durch vierfache Organoborierung von Tetra-1-alkinylsilanen und -germanen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1385-1396 
    Details
    ISSN: 0009-2940
    Keywords: Silanes, tetra-1-alkynyl- ; Germanes, tetra-1-alkynyl- ; 1,1-Ethyloboration, intermolecular ; 1,1-Vinyloboration, intramolecular ; Spirosilanes ; Spirogermanes ; Protodeborylation ; Transition metals, η41-complexes of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organosubstituted 1,1′-Spirobisiloles and 1,1′-Spirobigermoles by Fourfold Organoboration of Tetra-1-alkynylsilanes and -germanes[1]Si(C≡CR)4 [R=Me (A), R=Ph (B), R=SiMe3 (C)] and Ge(C≡CR)4 [R=Me (D), R=Ph (E)] react with Et3B by twofold intermolecular ethyloboration and twofold intramolecular vinyloboration to form the organo-substituted 5-sila(germa)spiro[4.4]nonatetraenes , R=Me: 1a, R=Ph: 1b; M=Ge, R=Me: 2d, R=Ph: 2e] via the mono-and bisethyloboration compounds 3 or 4 (e.g. 3b, 4c) with different rates: Ge 〉 Si; Me 〉 Ph. For comparison, compounds Sn(C≡CR)4 [R=Me (F), R=Ph (G)] react with Et3B in the absence of a solvent to mixtures of various spirotin compounds (5f, 5g, 6f, 8f, 9g, 10g, 11g) of which only 9g (R=Ph) corresponds to the spirosilanes and -germanes. This is the result of effective competition between intramolecular and intermolecular organoboration in the case of the tetra-1-alkynyltin compounds. The protodeborylation of 1a, b and 2d, e with MeCO2H leads to 12a, b and 13d, e, respectively. 12a isomerises by UV irradiation to allyl isomers 12a′. From 12a with 2 equiv. of maleic anhydride the 1:2 addition compound 14a is obtained, the autaddition of 12a, d leads to 15a, d. Spiro compound 12a reacts with (OC)5Fe or CpCo(C2H4)2 to give the cyclodiastereomeric η41-complexes [(OC)3Fe]2-12a (16a1-a4; X-ray structure analysis of meso- 16a1), (OC)3Fe-12a (17a) and (CpCo)2-12a (18a1-a4). - All products were characterized by multinuclear NMR, including measurements of the coupling constants 1J(13C13C), 2J(29Si29Si), nJ(29Si13C) and nJ(119Sn13C).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260617
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    Tri-, Tetramethylbullvalene und Hexamethylbibullvalenyl (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1419-1423 
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    ISSN: 0009-2940
    Keywords: Cope rearrangement ; Bullvalenes, tri-, tetramethyl- ; Bibullvalenyl, hexamethyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tri-, Tetramethylbullvalenes and HexamethylbibullvalenylThe known monomethylbullvalenes 6 and dimethylbullvalenes 7 are supplemented by tri-8 and tetramethylbullvalenes 9 as well as the hexamethylbibullvalenyl 10. The isomer distributions of the methylbullvalenes 6-9 are determined by NMR-spectroscopy. A vicinal arrangement of two methyl groups is not found. The 4-, 6-, 10-positions are slightly preferred in respect to the 3-, 7-, 9-positions. In the case of the methylbullvalenes 8 and 9 methyl groups occupy additionally the 1-, 2-, 8- but not the 5-position. Contrary to tetrabromobullvalenes 5, isomers of 9 show no pronounced kinetic stability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260622
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    Mono-, Di-, Tri-, Tetra-, Penta-und Hexaphenylbullvalene (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1429-1433 
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    ISSN: 0009-2940
    Keywords: Cope rearrangement ; Bullvalenes, mono-, di-, tri-, tetra-, penta-, and hexaphenyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mono-, Di-, Tri-, Tetra-, Penta-and HexaphenylbullvalenesLithium diphenylcuprate reacts with the corresponding bromobullvalenes to yield the phenylbullvalenes 1-6, whose substitution patterns are deduced from their 1H-NMR spectra. Starting with triphenylbullvalenes 3 some isomers show a relatively high kinetic stability which culminates in the case of the hexaphenylbullvalenes 6a and 6b in the loss of the phenomenon of fluctuating structure for the bullvalene skeleton.
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    URL: http://dx.doi.org/10.1002/cber.19931260624
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    Alkyleisen-und Alkylcobalt-Reagenzien, VII. Über die Substitution des Halogens von Alkenylchloriden, Alkenylfluoriden und Alkinylhalogeniden durch Reagenzien des Typs R4MLi2 (M=Fe, Co) (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1447-1452 
    Details
    ISSN: 0009-2940
    Keywords: Iron, organo complexes ; Cobalt, organo complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkyliron and Alkylcobalt Reagents, VII[1]. - On the Substitution of the Halogen of Alkenyl Chlorides, Alkenyl Fluorides, and Alkynyl Halides by Reagents of the Type R4MLi2 (M=Fe, Co)Me4FeLi2 and Me4CoLi2, which are favourable reagents for the substitution of Br in alkenyl bromides[1-4], also proved to be favourable for the substitution of the halogen in alkenyl chlorides (yields 68-99%; nearly complete retention of configuration in the case of Me4FeLi2), β1-fluorostyrene (best yield 92%), and 1-fluoronaphthalene (best yield 47%). Me4FeLi2 differentiates between various alkenyl chlorides in 1:1 competition experiments better than Me4CoLi2 and is the optimal reagent for the substitution of halogen in 1-chloro-2-phenylethyne (12), 1-bromo-2-phenylethyne (13), and 1-chloro-3-phenoxypropyne (15) by methyl (yields 70, 46, and 80%, respectively). Substitution of the halogen in 12 by the n1-butyl, n1-octyl, and phenyl residue is better achieved by the catalytic systems RMgBr + 2.5 mol % FeCl2 (R=nBu, nOct, Ph; yields 75, 63, and 96%, respectively) than by the reagents nBu4FeLi2, nBu4Fe(MgBr)2, nOct4Fe(MgBr)2, or Ph4Fe(MgBr)2 (yields 18-28%).
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931260627
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    Stereoselective Synthesis of α,β-trans1-Spiro-β1-lactones by Diels-Alder Cycloaddition of 1,3-Dienes to α1-Methylene-β1-lactone and Their Decarboxylation by Pyrolysis to (E)1-Alkylidenecycloalkenes, a Convenient Olefination Method (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1481-1486 
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    ISSN: 0009-2940
    Keywords: Stereoselectivity ; Diels-Alder reaction ; β1-Lactone ; α1-methylene- ; Spirolactones ; Alkylidene cycloalkenes ; Decarboxylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of spiro-β1-lactones was prepared in good to excellent yields through stereoselective [4 + 2] cycloaddition of β1-isopropyl-α1-methylene-β1-lactone (1) with acyclic, cyclic, heterocyclic and aromatic 1,3-dienes by sealed-tube reaction at moderate temperatures (50 - 130°C). Flash pyrolysis of the resulting spiro-β1-lactones 2 in the gas phase at 400°C afforded by decarboxylation exclusively the corresponding (E)1-isopropylidenealkenes in high yields with retention of the initial geometry and without double bond isomerization. This olefination method constitutes an excellent stereoselective synthesis of (E)1-alkylidenecycloalkenes.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260632
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    Synthesis of Macrocyclic Mercury(II) Derivatives of S,S′1-Trimethylene-and S,S′1-Tetramethylenebis(cis1-stilbene-α,β1-dithiol) with Unusual StructuresDedicated to Professor Klaus Hafner on the occasion of his 65th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1337-1340 
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    ISSN: 0009-2940
    Keywords: Macrocyclic (alkene dithiolato)mercury complexes ; Dithiolato complexes ; Stilbene-α,β1-dithiol complexes ; Mercury(II) macrocyclic dithiolato complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the ligand cis - -S—C(Ph)≡C(Ph)-S-[CH2]n - S - C(Ph)=C(Ph)-S- with n=3 (dianion of 1) with HgCl2 in ethanol produces a yellow linearly trinuclear, μ1-S and μ1-Cl-bridged complex of composition C62H52Cl2Hg3S8 (4), in which the central Hg(II) ion is in a near octahedral arrangement of four Hg—S and two Hg—Cl bonds, whereas the two terminal Hg(II) ions are tetracoordinated with three Hg—S bonds and one Hg—Cl bond in distorted tetrahedral arrangements. The two ligands are bidentate with respect to the terminal and central Hg(II) ions. The corresponding ligand with n=4 (dianion of 2) reacts with HgCl2 to yield a yellow Hg(II) complex of composition C32H28HgS4 (5), in which the ligand is tetradentate and in the trans-syn configuration. The Hg(II) ion in the unit cell of 5 is pentacoordinated, due to symmetric dimerization of two molecules of 2 by two weak coordinate Hg—S bonds of 3.442(2) Å length.
    Additional Material: 2 Ill.
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    Diorganomagnesium Compounds from Magnesium, Hydrogen, and 1-Alkenes and Their Application in Synthesis (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1371-1383 
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    ISSN: 0009-2940
    Keywords: Magnesium hydride, catalytically prepared ; Hydromagnesation reactions ; Magnesium, diorgano compounds, preparation from magnesium, hydrogen and 1-alkenes ; Magnesium, diorgano compounds, application in syntheses ; Magnesium, diorgano compounds, oxidation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Alkenes are converted in high yields to the corresponding primary diorganomagnesium compounds by transition metalcatalyzed hydromagnesation reaction using catalytically prepared suspended (MgH2*) or dissolved magnesium hydride (MgH2*). The most active hydromagnesation catalysts have been found to be combinations of zirconium tetrahalides with MgH2* or MgH2*. The reaction is highly regio-and chemoselective. The diorganomagnesium compounds prepared in situ from magnesium, hydrogen, and 1-alkenes can be applied to the synthesis of organic and organometallic compounds just as Grignard compounds (Scheme 3, reaction 3-11). Dioctylmagnesium undergoes the growth reaction with ethene in the presence of quinuclidine and is oxidized by molecular oxygen in high yield to 1-octanol.
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    Synthesis of tetrakis[(tri-tert-butylphosphane)gold(I)]phosphonium salts and crystal structure of the tetraphenylboroxinate salt {[(tBu)3PAu]4P}+ [O(PhBO)2BPh2] -  (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2033-2036 
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    ISSN: 0009-2940
    Keywords: Gold complexes ; Phosphonium, tetrakis[(tri-tert-butylphosphane)gold(I)] ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of (Me2Si)3P with {[(tBu)3PAu]3O}+ BF4- in tetrahydrofuran at  - 78C affords the compound {[(tBu)3-PAu]4P}+ BF4 -  (1a) in high yield. This product is converted into the tetraphenylborate salt (1b) by treatment with Na[BPh4]. The two compounds have been identified on the basis of their analytical and spectroscopic data, but could not be crystallized. In attempts to prepare single crystals of 1b, a crystalline salt {[(tBu)3PAu]4P}+ [O(PhBO)2BPh2] -  (1c) has been obtained in very small quantities, probably by partial anion hydrolysis. A single crystal X-ray diffraction study of 1c CH2Cl2 shows the compound to be built up of cations with a strongly distorted tetrahedral (PAu)4P skeleton and anions with a planar six-membered boroxine ring. Two of the phenyl groups are attached to two trigonal-planar boron atoms and the other two phenyl groups to the third (tetrahedral) boron atom of the heterocycle. The origin of the peculiar cation structure is discussed in the light of findings with related ammonium- and arsonium-centered gold clusters.
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    Beiträge zur Chemie des Imidazols, III. 2-Telluroimidazoline  -  stabile Tellurocarbonyl-Verbindungen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2047-2049 
    Details
    ISSN: 0009-2940
    Keywords: 2-Telluroimidazolines ; 125Te NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imidazole Chemistry, III[1].  -  2-Telluroimidazolines  -  Stable Tellurocarbonyl Compounds2-Telluroimidazolines 6 are obtained as stable solids from the imidazol-2-ylidenes 4 and tellurium in good yields. The X-ray structure of 6c reveals the relevance of the mesomeric structure 5 [d(C1 - Te) = 2.087(4) Å] which is confirmed by the upfield shift in the 125Te NMR spectra (dL 〈  - 150).
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    URL: http://dx.doi.org/10.1002/cber.19931260914
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    Phosphorus-centered gold clusters: A novel pentanuclear species {[(Ph3P)6Au5]P}2+ (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2037-2040 
    Details
    ISSN: 0009-2940
    Keywords: Gold cluster, phosphorus-centered ; Phosphanegold(I) complex ; Phosphorus, hypercoordinate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of tris[(triphenylphosphane)gold]oxonium tetrafluoroborate with phosphane gas in tetrahydrofuran leads to a mixture of products, one of which has now been isolated and identified as the complex {[(Ph3P)6Au5]P}2+ (BF4 - )2 (1). This cluster can be described as an adduct of [(Ph3PAu)4P]+ and [(Ph3P)2Au]+. Crystals of (1)2 (CH2Cl2)3 Et2O contain two crystallographically independent formula units of very similar structure. The dications are centered by pentacoordinate phosphorus atoms in an irregular coordination geometry. In the crystal one of the five gold atoms is attached to two triphenylphosphane ligands, while the other four bear only one such ligand. In solution rapid ligand exchange renders the ligands equivalent on the NMR time scale. This stoichiometry and structure of 1 are indicative of the strong basicity of the [(Ph3PAu)4P]+ cation probably owing to its square-pyramidal structure with strong Auä bonding, as suggested by the structure of its arsenic analogue.
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    Flüssigkristalline Verbindungen, 77. Neue makroheterocyclische Palladium-Komplexe (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1253-1255 
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    ISSN: 0009-2940
    Keywords: Cyclopalladations ; Liquid crystals ; Mesophases ; Metallomesogens ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid Crystals, 77[1]. - Novel Macroheterocyclic Palladium ComplexesThe double cyclopalladation of the bisimine 1 affords spacious tetrapalladium complexes 2a - c which represent new thermotropic metallomesogens, the heaviest low-molecular liquid crystals (mol. mass ≍ 3500 - 4000) studied so far.
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19931260601
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    Ligand-Induced Hydrogen Scrambling and Interligand Carbon - Carbon Bond Formation in the Gas-Phase Reactions of MCH3+ (M=Fe, Co) with 1-Octyne and 1-OcteneDedicated to Professor Jochanan Blum on the occasion of his 60th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1257-1260 
    Details
    ISSN: 0009-2940
    Keywords: Transition-metal chemistry ; Bond activation; C - H and C - C bonds ; Fourier-transform ion-cyclotron resonance ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Evidence is presented that the encounter complexes of MCX3+ (M=Fe, Co; X=H, D) with 1-octyne, prior to C - H-and C - C bond activation, undergo interligand C - C bond coupling as well as extensive hydrogen exchange. In distinct contrast, in the related complexes formed by gas-phase reaction of MCX3+ (M=Fe, Co; X=H, D) with 1-octene, the metal-methyl group retains its identity while the alkene ligand is subject to extensive hydrogen scrambling presumably by β1-hydrogen shift to and from the metal centers.
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    Darstellung und Reaktionen von 1,1,2,2-Tetraborylethan-DerivatenHerrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1291-1297 
    Details
    ISSN: 0009-2940
    Keywords: Ethane, 1,1,2,2-tetraboryl- ; 2,2--Bis(2,3-dihydro-1,3-diborole) ; 1,2,5-Phosphadiborolane ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Reactions of 1,1,2,2-Tetraborylethane DerivativesHerrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet.Reaction of (Z)1-1,2-bis(dichloroboryl)ethene with B2Cl4 leads to 1,1,2,2-tetrakis(dichloroboryl)ethane (1a) in 90% yield. Substitution of the chlorine atoms in 1a results in the formation of the iodo and amino derivatives 1b and 1c, d. Compound 1b reacts with alkynes to give the 2,2′-linked 2,3-dihydro-1,3-diborole derivatives 2b, c which are aminated to yield 2d, e. Dehalogenation of 1d leads to the organoboron C2B4 cage 3d. The heterobicyclic compound 4d with two fused phosphadiborolane rings is obtained from 1d and LiPH2. Reaction of 4d with (CO)3Fe(C8H14)2 gives the unusual diiron complex 5d. The constitutions of the new compounds are derived from spectroscopic data and are proven for 2e, 4d and 5d by X-ray structure analyses.
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    Quantum-Mechanical ab initio Investigation of the Transition-Metal Compounds OsO4, OsO3F2, OsO2F4, OsOF6, and OsF8 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1325-1330 
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    ISSN: 0009-2940
    Keywords: Osmium tetroxide ; Osmium fluoride oxides ; Osmium octafluoride ; Calculations, ab initio ; Pseudopotentials ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equilibrium geometries of OsO4, OsO3F2, OsO2F4 and OsF8 are theoretically predicted by using quantum-mechanical ab initio methods at the Hartree-Fock and MP2 level of theory employing quasi-relativistic pseudopotentials for Os and 3-21G and 6-31G(d) basis sets for O and F. A comparison of the calculated geometries and vibrational frequencies with available experimental results shows a good agreement. The energy minimum structure for OsO4 has Td symmetry, for OsO3F2 it has D3h symmetry, for OsO2F4 C2v symmetry with cis1-coordinated oxygen atoms, and for OsF8 a D2d symmetry with two different Os - F bond lengths is predicted. OsOF6 is not a minimum on the potential energy hypersurface. The calculation of the thermodynamic stabilities indicates that the Os - F bond in OsF8 is clearly weaker than in OsO3F2, OsO2F4 and in OsF6. It will be very difficult to observe OsF8 experimentally. The analysis of the electronic structure shows that the Os - O bond is partly covalent, while the Os - F bonds are mainly ionic.
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    OsO3F2 and OsO2F4, Preparation and Crystal Structures (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1331-1336 
    Details
    ISSN: 0009-2940
    Keywords: Osmium difluoride trioxide, preparation, structure ; Osmium tetrafluoride dioxide, preparation, structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new method for preparing OsO3F2 is presented. Its crystal structure reveals a polymeric chain structure with distorted octahedral geometry for the OsO3F3 units and symmetrical, non-linear fluorine bridges. The OsO3F3 unit has a facial geometry. This structure is not in accord with predictions on the molecular structure of OsO3F2. OsO2F4, obtained from KrF2 and OsO4, crystallizes in the space group P61 forming a sixfold helical chain arrangement of nearly octahedral OsO2F4 molecules. Oxygen or fluorine atoms are partially disordered. The cis orientation of the two oxygen atoms is established by means of NMR, vibrational spectroscopy, and X-ray data.
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    Ein einfacher Weg zur Herstellung von Alkylpalladium-Verbindungen durch Pd—O-Bindungs-Spaltung in kationischen Bis(ether-phosphan)palladium(II)1-Komplexen mit Grignard-ReagenzienHerrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1347-1353 
    Details
    ISSN: 0009-2940
    Keywords: Palladium complexes, alkyl-and acyl- ; Ether phosphanes ; Fluxional behavior ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Method for the Preparation of Alkylpalladium Compounds by Pd—O Bond Cleavage in Cationic Bis(etherphosphane)palladium(II) Complexes with Grignard ReagentsHerrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet.The bis(chelate) complexes [Pd(P∩O)2][ClO4]2 (3a - e) react with methylmagnesium chloride with a concomitant cleavage of two weak Pd—O bonds to give the methyl complexes trans1-ClPd(P∼O)2(CH3) (4a - e) (P ∼ O; η1-P1-coordinated; P∩O: η21-O, P1-chelated; Scheme 1). Diffusion of pentane into the reaction mixture of 4a-e in the presence of the formed magnesium salts yields the cationic complexes trans-[Ch3Pd(P∼O)1-(P∩O)][ClO4] (6a, c). The reaction of 3a-e with benzylmagnesium chloride affords the cationic benzyl complexes cis-[PhCh2Pd(P∼O)(P∩O)][ClO4] (8a-e) in which only one Pd—O bond has been cleaved. In the presence of carbon monoxide 4a-e adn 6a, c are transformed into the corresponding acyl complexes CH3C(O)Pd(P∼O)2Cl (5a-e and [CH3C(O)Pd-(P∼O)(P∩O)][ClO4] (7a, c). Whereas at 183 K variable-temperature 31P{1H}1-NMR measurements of 6a, c, 7a, c indicate a non-rigid behavior of the two differently bound ether-phosphanes, the dynamic process is frozen out for 8a-e. By a lineshape analysis of the spectra the thermodynamic parameters ΔG≢, ΔH≢, and ΔS≢ are obtained. According to a crystal structure analysis 3d and 6c crystallize in the monoclinic space group P21/c with Z=4.
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    Halogen - Kohlenstoff - Schwefel-Verbindungen: Synthesen mit 2-Methylthio-4,5-bis(trifluormethyl)-1,3-dithiolium-trifluormethansulfonat (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2111-2118 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Dithiolium salts, 2-amino-, 2-methylthio- ; Reactions with phenoles and active methylene compounds ; Hydration ; 1,3-Dithioles ; Phosphonium salts ; Phosphoranes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Halogen - Carbon - Sulfur Compounds: Syntheses with 2-Methylthio-4,5-bis(trifluoromethyl)-1,3-dithiolium TrifluoromethanesulfonateBy reactions of the strongly electrophilic 2-methylthio-4,5-bis-(trifluoromethyl)-1,3-dithiol-2-ylium trifluoromethanesulfonate (6) with nucleophiles like secondary amines, phenoles and active methylene compounds the new 2-amino-1,3-dithiolium salts 11 a - e and 1,3-dithiol-2-ylidene compounds 5-10, 12 were obtained. The 1,3-dithiolium salts 14 were prepared in two different ways. Reaction with PPh3 yields the phosphonium salt 16, from which the ethylidene compound 20 was obtained via the intermediate phosphorane 18. The crystal structures of 7, 16 and of the fulvalene 19 were determined.
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    URL: http://dx.doi.org/10.1002/cber.19931260922
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    Alkylvanadium- und Alkylniob-Reagenzien, III. über zwei unkonventionelle Methoden zur Charakterisierung labiler Organoübergangsmetall-Komplexe; Anwendungen auf Allylderivate von VIII, VV, CrIII und MnII (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2093-2100 
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    ISSN: 0009-2940
    Keywords: Allyl compounds ; Crotyl compounds ; Vanadium chlorides, organo ; Chromium chlorides, organo ; Manganese chlorides, organo ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylvanadium and Alkylniobium Reagents, III[1]. - Two Unconventional Chemical Methods for the Characterisation of Labile Transition Metal Complexes; Application to Allyl Derivatives of VIII, VV, CrIII, and MnIITwo little known chemical methods, the “Competition Constant Method” and the production of “Ligand Concentration/Product Yield Diagrams”, are suitable for the characterisation and identification of allyl and crotyl transition metal species prepared in solution. These methods (Figures 1 - 6) gave the following results: by transmetallation of 1 or 2 equivalents of allylMgBr with 1 equivalent of VCl3, CrCl3, or MnCl2 and subsequent reaction with ketones, a diallyl (2, 23, 25) and not a monoallyl derivative of the transition metal reacts with the ketones, suggesting that the equilibrium: 2 allylMCI (allyl)2M + MCl2 (M = VCl, CrCl, Mn) lies far to the right hand side. This assumption was confirmed by the IR spectrum in the case of vanadation of 1 and 2 equivalents of allylMgBr with VCl3 and corresponds with the observation that by chromation of allylMgBr with 1 equivalent of CrCl3 ca. 50% of the CrCl3 remain unaffected although the allylMgBr is completely consumed. Conversely, according to the results of the “Competition Constant Method” vanadation of 1, 2, or 3 equivalents of allylMgBr with VOCl3 gives three different allyl complexes which are believed to be allylVOCl2 (5), (allyl)2VOCl (6), and (allyl)3VO (7). Vanadation of 1 or 2 equivalents of crotylMgBr with 1 or 2 equivalents of VCl3 gives analogous results to the corresponding reactions with allylMgBr.
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    Dendrimere Polyamine (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2133-2135 
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    ISSN: 0009-2940
    Keywords: Cobalt complex ; Dendrimer ; Divergent synthesis ; Dendritic amines ; Nitrile reduction ; Schiff base ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dendrimeric PolyaminesThe dendritic amines 2, 3, 4 and the imine 6 are synthesized by a divergent strategy. The formerly problematic reduction of polynitriles is achieved by the use of diisobutylaluminium hydride in high yield. The functional imine dendrimer 6 is converted into its tricobalt complex 7.
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    A group 4 metallocene template synthesis of β,γ-unsaturated ε-hydroxy carboxylic acids (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2119-2126 
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    ISSN: 0009-2940
    Keywords: Zirconocene complexes ; (Metaloxy)carbene complexes ; Template reaction, organometallic ; Steroid side-chain attachment ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of (butadiene)zirconocene with hexacarbonyltungsten gives the metallacyclic [(π-allyl)zirconoxy]carbene complex 7. This reagent adds to a variety of ketones to yield chiral nine-membered metallacyclic ring systems (8). These systems are thus formed by means of 1,4-selective coupling reactions of 1,3-butadiene with W(CO)6 and an organic carbonyl compound at the zirconocene template. The ketones subjected to react with 7 include benzophenone, methyl vinyl ketone, cyclopentanone, and 3-methoxyestra-1,3,5(10)-trien-17-one (12). The coupling products of 7 with cyclopentanone (8c) and 12 (8d-A) were characterized by X-ray crystal structure analyses. Of the four possible diastereomeric nine-membered metallacyclic coupling products of 7 with 12 a single isomer [8d-A with (13'S,17'R,2,3,4-pS) configuration] was formed with ≥98% selectivity and isolated in 95% yield. Treatment of the complexes 8 in tetrahydrofuran with water and pyridine N-oxide very effectively removed both transition metals with the formation of the corresponding β,γ-unsaturated ε-hydroxy carboxylic acids. The overall reaction sequence has thus converted the steroid ketone 12 very selectively to 5-[3-methoxy-17β-hydroxyestra-1,3,5(10)-trien-17α-yl]-(E)-pent-3-enoic acid (10d)
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    Metallorganische Clusterkomplexe mit flächenüberbrückenden Aren-Liganden, 5[1a]. C-H-Aktivierung und Bildung eines μ3-Aren-Komplexes: Konkurrenzreaktionen beim Aufbau von (CpCo)3-Clusterkomplexen mit Vinylbenzolen als Liganden (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1615-1618 
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    ISSN: 0009-2940
    Keywords: Cyclopentadienylcobalt ; Alkyne cluster ; Arene cluster ; Bond activation, C-H ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Clusters with Face-Capping Arene Ligands, 5[1a].-C-H Activation and Formation of a μ3-Arene Complex: Competing Reactions During Assembly of (CpCo)3 Cluster Complexes with Vinylbenzenes as LigandsA number of ring-substituted styrenes R(C6H4)C2H3 (R=CH3, F) reacts with [CpCo(C2H4)2] (1) to give both the cluster complexes [(CpCo)3{μ3-η2:η2:η2-(C6H4R)C2H3}] [2a (R=p-CH3), 2c (R=m-F), 2d (R=p-F)} with Co3 face-capping arenes and [(μ2-H)(μ3-H)(CpCo)3{μ3-1-s̰:2-s̰:η2-HCC(C6H4R)}] [7a (R=p-CH3), 7b (R=o-F), 7c (R=m-F), 7d (R=p-F)] with Co3 face capping alkynes derived from dehydrogenation of the vinyl group. The X-ray structure analysis of 7a confirms the 1-s̰:2-s̰:η2 coordination of the bridging alkyne ligand. In solution the complexes 7 are fluxional and exhibit migration of the alkyne and hydride ligands on the Co3 cluster.
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    Desaminierungsreaktionen, 54. Zerfall von 1-Cyan-1-propandiazonium-Ionen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1499-1502 
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    ISSN: 0009-2940
    Keywords: α1-Cyanodiazonium ions ; α1-Cyanoalkyl radicals ; Carbocations, destabilized ; Substitution, nucleophilic ; Deamination reactions ; Diazonium ions ; Radicals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deamination Reaction, 54[1]. - Decomposition of 1-Cyano-1-propanediazonium IonsThe nitrous acid deamination of 2-aminobutanenitrile (9) was studied with regard to product distribution and stereochemistry. The formation of 2-(hydroxyimino)butanenitriles (21, 22; 8 - 28%) indicates the intervention of 1-cyanopropyl radicals (24) that are captured by NO. The polar reactions lead mainly to elimination (10 - 13) and nucleophilic substitution (14 - 16), rearrangement playing a minor role. (R)-9 was prepared from (R)1-2-aminobutanoic acid. The nitrous acid deamination of (R)-9 afforded the cyanohydrin 16 with 81% net inversion. Owing to destabilization of the carbocation 26 by CN, the SN2 route of nucleophilic displacement is preferred over SN1. The influence of CN is shown to be smaller than that of CF3.
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    Desaminierungsreaktionen, 55. Zerfall von 2-Cyannorbornan-2-diazonium-Ionen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1503-1508 
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    ISSN: 0009-2940
    Keywords: α1-Cyanodiazonium ions ; Carbocations, destabilized ; Wagner-Meerwein rearrangement ; 6,2-H Shifts ; Stereoselectivity ; Diazonium ions ; Deamination reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deamination Reactions, 55[1]. - Decomposition of 2-Cyanonorbornane-2-diazonium IonsThe epimeric 2-aminonorbornane-2-carbonitriles (8a and 9a) were prepared from norbornane-2-one (7). The nitrous acid deamination reactions of 8a and 9a afforded the nitro compounds 15c and 16c in low exo/endo ratios, presumably by way of 2-cyano-2-norbornyl radicals (12). The major ionic process was found to be a Wagner-Meerwein rearrangement, leading to 1-cyano-2-norbornyl cations (10) and products 14 derived therefrom. Minor amounts (≤10%) of 2-hydroxynorbornane-2-carbonitriles (15a, 16a) provide suggestive, albeit inconclusive evidence for the trapping of 2-cyano-2-norbornyl cations (11). The decomposition of the endo diazonium ions 9c is also associated with norbornyl → norpinyl rearrangement, giving rise to 17 (≤9%). Stereochemical studies with optically active precursors point to intervention of the 7-bridged norbornyl cation 13 and of the edge-protonated cyclopropane 25. The formation of both species is clearly promoted by the cyano group.
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    Pseudoazulene als Dienophile in der [4 + 2]-Cycloaddition mit inversem Elektronenbedarf (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2143-2147 
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    ISSN: 0009-2940
    Keywords: Pseudoazulenes ; 1,2,4,5-Tetrazines ; [4 + 2] Cycloadditions, two-step ; 14π-Hetarenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudoazulenes as Dienophiles in the [4 + 2] Cycloaddition with Inverse Electron Demand[4 + 2] Cycloadditions of the pseudoazulenes 2, 6, 13, 18, and 22 to the extremely electron-deficient s-cis-fixed diazadiene system of 3,6-bis(trifluoromethyl)-1,2,4,5-tetrazine (1) are described. Probably according to a two-step mechanism the pseudoazulenes 2, 6, and 18 react with 1 to form the corresponding cycloadducts followed by elimination of nitrogen and oxidation to furnish the novel 14 systems 5, 12, and 21 in rather high yields. In contrast, with the cyclopenta[d]-pyridazines 13 and 22 the azines 17 and 26, respectively, are formed exclusively.
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    Phosphanalkylene, 54[1a]. Kumulierte ylide, 21[1b]. Ein neuer weg zu N-substituierten (triphenylphosphoranyliden)keteniminen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2151-2153 
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    ISSN: 0009-2940
    Keywords: Phosphonium ylides, cumulated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphane Alkylenes, 54[1a]. - Cumulated Ylides, 21[1b]. - A New Way to N-Substituted (Triphenylphosphoranylidene)-keteniminesReaction of methylenetriphenylphosphorane (1) with isothiocyanates 5 leads to ylides 6B, which can be methylated at the S atom to give the phosphonium salts 8. Treatment of 8 with sodium methanolate gives rise to formation of the phosphoranes 10, which on treatment with sodium bis(trimethylsilyl)-amide undergo β-elimination to form the N-substituted (tri-phenylphosphoranylidene)ketenimines 3.
    Additional Material: 1 Tab.
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    Pyrano[4,3-b]pyran-2,5-dione, 1  -  Einfache Synthese von Pyranopyrano-chinolintrionen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2155-2155 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260930
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    Masthead (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261001
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  • 151
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    CFNO-Isomere  -  Theoretische und experimentelle Studien (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2167-2176 
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    ISSN: 0009-2940
    Keywords: Calculations, ab initio ; Fluoroisocyanate ; Matrix isolation ; Normal coordinate analysis ; Photochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CFNO Isomers  -  Theoretical and Experimental StudiesGeometrical parameters, relative thermodynamic stabilities, and vibrational wavenumbers have been calculated for six CFNO isomers by using various ab initio methods. The results are compared with those of the respective CHNO species. In noble gas matrices the most stable CFNO isomer fluoroisocyanate, FNCO, was prepared by photolysis of FC(O)N3 as well by the reaction FN + CO and FCN + O. The short-lived intermediate (fluorocarbonyl)nitrene, FC(O)N, formed during photolysis of FC(O)N3, was trapped as FC(O)NCO in a CO matrix. In each case the courses of the investigated matrix reactions were rationalized by identification of nearly all products and the time dependence of their formation. For the FNCO molecule a complete vibrational spectrum including 15N-, 13C-, and 18O-isotopic data was measured which enabled calculation of its general valence force field.
    Additional Material: 7 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931261003
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    Konkave Makroheterocyclen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1713-1721 
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    ISSN: 0009-2940
    Keywords: Concave molecules ; Cyclophanes ; High-dilution principle ; Macrocycles ; Spheriphanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concave MacroheterocyclesMacrocyclic compounds of the general type 2 having a spherical shape and a molecular cavity have been synthesized. A „fold and paste“-type cyclization step generates the macroheterocycles 4, 10, 11, 14, and 21. Since this approach is difficult to apply for O-substituted derivatives, the „spheriphane“ 24 was synthesized by intermolecular cyclizaiton. The X-ray structure analysis of 11 shows intermolecular interactions („dimer formation“) in the crystal.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260731
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    Auf dem Weg zu makrocyclischen para-Phenylenen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1723-1732 
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    ISSN: 0009-2940
    Keywords: Cyclohexanes ; Cyclohexanones ; Cyclophanes ; Macrocycles ; Paracyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Way to Macrocyclic para-PhenylenesStrategies are presented to synthesize the hitherto unknown [On]Paracyclophanes 1. Open chain belt-type molecules based on 1,4-connected carbocyclic six-membered rings were prepared. Functionalization of the outer rings in 4-position is the prerequisite for cyclization or lengthening of the molecular belts. In order to obtain the macrocyclic target molecules 1, well preorganized cis-isomers of 1,4-disubstituted cyclohexanes were prepared. X-ray structural analyses reveal the static stereochemistry of the intermediates 8, 9, 17, 18, and 24. The macrocyclic hydrocarbon 29 containing five cyclohexylidene units was detected.
    Additional Material: 3 Ill.
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    Synthese mittlerer und großer Ringe, XXXIII[1]. Optisch aktive 3a,6-Methanohydroazulene durch chirale Induktion der photochemischen Festkörperumlagerung von Bis(1,2:5,6-di-O-isopropyliden-α-D- und -α-L-glucofuranos-3-O-yl)-3,6-hexanooxepin-4,5-dicarboxylat (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1733-1742 
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    ISSN: 0009-2940
    Keywords: 3,6-Alkanooxepine-4,5-dicarboxylic esters, optically active ; Methanohydroazulenes ; Photochemistry, solid-state ; CD spectra ; Absolute configuration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Medium and Large Rings, XXXIII[1].-Optically Active 3a,6-Methanohydroazulenes via Chiral Induction of the Solid-State Photochemical Rearrangement of Bis(1,2:5,6-di-O-isopropylidene-α-D- and -α-L-glucofuranos-3-O-yl) 3,6-Hexanooxepine-4,5-dicarboxylateIrradiation of an aqueous suspension of the crystalline 3,6-hexanooxepine-4,5-dicarboxylic esters 2a and 2b affords the (3aS,6R,8aR)- and (3aR,6S,8aS)-methanohydroazulenes 3a and 4b in 54-58% yield with 92-93% de. Irradiation of an ethereal solution of 2a-2d on the other hand proceeds with low diastereoselectivity. The absolute configurations were established by X-ray structural analysis of the dimenthyl ester (+)-3d, comparison of CD spectra and chemical transformations. The origin of the high diastereoselectivity of the rearrangements 2a → 3a and 2b → 4b in the solid state is discussed on the basis of the X-ray structural analysis of the 3,6-heptanooxepine (-)-5a. Procedures for the removal of the chiral auxiliaries are described. Di-O-isopropylidene-α-L-glucofuranose is recycled in 95% yield.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260733
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    Metallkomplexe mit funktionalisierten Schwefel-Liganden, VI[1]. Stabilisierung von 1-Alkin-1-thiolato-Liganden [R-C≡C-S-; R = SiMe3,(η5-C5H4)Fe(η5-C5H5)] in Ru(II)- und Pt(II)-Komplexen. Kristallstrukturanalyse von cis-(Ph3P)2Pt[C≡C-(η5C5H4)Fe(η5-C 5H5)]2Herrn Professor Dr. Dr. h. c. mult. Heinrich Nöth zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1807-1809 
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    ISSN: 0009-2940
    Keywords: 1-Alkyne-1-thiolato ligands ; Bis(acetylide) complexes ; Ferrocene derivatives ; Ruthenium complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Functionalized Sulfur-Containing Ligands, VI[1]. - Stabilization of 1-Alkyne-1-thiolato Ligands [R-C≡C-S-; R = SiMe3, (η5-C5H4)Fe(η5-C5H5)] in Ru(II) und Pt(II) Complexes. X-ray Structure Analysis of cis-(Ph3-P)2Pt[C≡C-(η5-C5H5)]2The 1-alkyne-1-thiolates R-C≡C-SLi [1: R = SiMe3, 3: (η5-C5H4)Fe(η5-C5H5)] react with (Ph3P)2PtCl2 and CpRu(PPh3)2Cl to give the complexes trans-(Ph3P)2Pt(S-C≡C-SiMe3)2 (4a), CpRu(PPh3)2(S-C≡C-SiMe3) (4b), and cis-(Ph3P)2Pt[S-C≡C-η5-C5H4)Fe(η5-C5H5)]2 (5). The Pt(II) bis(acetylide) complex cis-(Ph3P)2Pt[C≡C-(η5-C5H4)Fe(η5-C5H5)]2 (6a) was isolated after chromatography of 5. The trans-configurated compound 6b is obtained by the reaction of [LiC≡C-(η5-C5H4)]Fe(η5-C5H5) with (Ph3P)2PtCl2. The complexes are characterized by IR, 1H-, 13C-, and 31P-NMR spectroscopy, FAB mass spectrometry and X-ray diffraction (6a).
    Additional Material: 1 Ill.
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    Preparation of Benzo-diimidazoles and Benzo-triimidazoles (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1819-1822 
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    ISSN: 0009-2940
    Keywords: Benzo-triimidazoles ; Benzo-diimidazoles ; Benzenehexamine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of benzenehexamine (1), benzene-1,2,3,4-tetramine (4), and benzene-1,2,4,5-tetramine (6) with aryl isocyanate 2 afforded the corresponding hexakis(N'-arylureido)benzene 3 and the tetrakis(N'-arylureido)benzenes 5 and 7. Pyrolysis of 3, 5, and 7 at 400°C furnished the benzo-triimidazoletrione 8 and benzo-biimidazolediones 10 and 11.
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    Kleine Ringe, 77[1]. Erzeugung und Abfangreaktionen von Cyclobutadientetracarbonsäure-tetramethylester (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1827-1833 
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    ISSN: 0009-2940
    Keywords: Photochemistry ; β-Elimination ; Diels-Alder reaction ; Cage compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 77[1]. - Generation and Trapping Reactions of Tetramethyl CyclobutadienetetracarboxylateDibromocyclobutane derivates 6 and 7 serve as precursors for the generation of the title compound 1. In the presence of suitable reagents 1 can be trapped in Diels-Alder additions. Photocyclization of the adducts can be used for the construction of polyfunctionalized cage compounds.
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    URL: http://dx.doi.org/10.1002/cber.19931260813
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    Darstellung und optische Eigenschaften endständig substituierter Polyene mit Androstan als Spacer (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1683-1691 
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    ISSN: 0009-2940
    Keywords: Polyenes, conjugated ; Bichromophores ; Steroid (androstane) as spacer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Optical Properties of Terminally Substituted Conjugated Polyenes with Androstane as SpacerThe conjugated polyenes 10, 11, 21, 22, and 26 with 9-anthryl and 2-tetraphenylporphyrinyl (TPP) terminal groups and an androstane unit incorporated into the polyene chain were synthesized by Wittig or Wittig-type olefinations. In most but not all cases the desired all-(E) isomers could be obtained from the (E)/(Z)-isomeric mixtures by chromatographic purification. From the UV/Vis spectra it is concluded that in all cases the TPP group and the polyene chain are electronically separated, whereas the 9-anthryl residue and the connected dienyl moiety in 10 and 11 are electronically amalgamated. In 21, 22, and 26 a selective excitation of the anthryl group, the TPP moiety, and the polyene is possible.
    Additional Material: 2 Ill.
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    Über (Pentafluorphenyl)thiocarbonyl-Verbindungen sowie die Synthese und Struktur von (Pentafluorphenyl)phenylsulfin (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1701-1706 
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    ISSN: 0009-2940
    Keywords: Thiocarbonyls, (pentafluorophenyl)- ; Sulfine ; Pentafluorothiobenzaldehyde anthracene adduct ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Pentafluorophenyl)thiocarbonyl Compounds, Synthesis and Structure of Pentafluorophenyl Phenyl SulfineThe C6F5-substituted thiocarbonyls C6F5-CS-R [R=C6H5 (2), CH3 (4)] are synthesized from the corresponding carbonyl compounds by using in situ formed B2S3. The corresponding highly reactive thioaldehyde (R=H) is trapped with anthracene as Diels-Alder adduct 7. By oxidation of 2 sulfine 10 is generated which dimerizes in the crystal lattice. An X-ray crystal structure determination of a trithiaphosphinane 9 was carried out for the first time. The bis-para-substituted compound 12 is obtained from perfluorobenzophenone and hydrazine hydrate in a fast reaction.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260729
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    Flüssigkristalline Verbindungen, 79[1a]. Amphiphile und mesogene Kohlenhydrate, V[1b]. Amphiphile Fluorglucose- und Fluorscyllitol-Derivate (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1707-1712 
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    ISSN: 0009-2940
    Keywords: Amphiphiles ; Carbohydrates ; Fluoro-D-glucoses ; Fluoro Sugars ; Liquid crystals ; Mesogens ; Scyllitol derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid Crystalline Compounds, 79[1a].-Amphiphilic and Mesogenic Carbohydrates, V[1b].-Amphiphilic Fluoroglucose and Fluoroscyllitol DerivativesIn order to look at the influence of the OH-F substitution in the cyclic, hydrophilic section (head group) of amphiphilic sugars and of scyllitol derivatives on their liquid crystalline properties for the first time, we synthesized various differently structured fluoro-D-glucose derivatives [2-O-decyl-α-D-glucopyranosyl fluoride (4), 4-O-tetradecyl-α-D-glucopyranosyl fluoride (5), 6-O-hexadecyl-α-D-glucopyranosyl fluoride (6), 6-deoxy-6-fluoro-2,3-di-O-hexadecyl-D-glucopyranose (9), 2-deoxy-2-fluoro-4,6-O-alkyliden-D-glucopyranosen (11a-d), 3-deoxy-3-fluoro-5,6-di-O-tetradecyl-D-glucofuranose (15)] as well as the 2-deoxy-2-fluoro-2,3,4,5,6-tetra-O-hexyl-scyllo-in-osit (19). Substitution of an OH group for a fluorine atom in amphiphilic derivatives destabilizes the thermotropic mesophase as it was to be expected so that either no or only narrowrange mesophases result. Both thermotropic and lyotropic liquid crystal phases occur in the series of 2-deoxy-2-fluoro-D-glucopyranose acetals 11 which are discussed in detail and which are compared with the analogous 2-hydroxy derivatives 12. Only 11c-d are thermotropic fluoro mesogens.
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    Cycloadditionen von 6H-1,3,4-Oxadiazin-6-onen (4,5-Diaza-α-pyronen), 13[1]. Diels-Alder-Reaktionen mit 6H-1,3,4-Oxadiazin-6-onen als Dienophil (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1743-1748 
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    ISSN: 0009-2940
    Keywords: 6H-1,3,4-Oxadiazin-6-ones ; 1,2-Bismethylenecyclohexane ; Diels-Alder reactions ; [1,3,4]Oxadiazino[4,5-b]isoquinolin-1-one derivatives ; Bicyclo[2.1.1]hexan-5-one, highly substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloadditions of 6H-1,3,4-Oxadiazin-6-ones (4,5-Diaza-α-pyrones), 13[1].-Diels-Alder Reactions with 6H-1,3,4-Oxadiazin-6-ones as Dienophile2,5-Diphenyl-1,3,4-oxadiazin-6-one (1b) reacted as dienophile with 2,3-dimethyl-1,3-butadiene to afford the pyridooxadiazinone 5. Analogously, the oxadiazinoisoquinolines 7c- e were formed on treatment of 2-(4-nitrophenyl)- (1c), 2-(4-tolyl)- (1d), and 2-(4-bromophenyl)-5-phenyloxadiazinone (1e) with 1,2-bis(methylene)cyclohexane (6). In contrast, the methyl oxophenyloxadiazinecarboxylate 1a gave a low yield of the cyclopentenone derivative 8 and 7a in the ratio 2.3:1.0. A third type of product, i.e. the cyclobutanone derivative 9, resulted on exposure of the anisyl(isopropyl)oxadiazinone 1f to 6. The oxadiazinones 1d, e, f have been prepared for the first time. X-ray structure analyses established the identity of the compounds 7d and 9.
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    Free-Radical Coupling of Alkyl and Aryl Halides with Electron-Deficient Alkenes Mediated by Chromium(II) Complexes[1] (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1759-1761 
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    ISSN: 0009-2940
    Keywords: Bond formation, C-C ; Chromium(II) complexes ; Radicals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free radicals generated from organic halides and (ethylenediamine)chromium(II) complexes in DMF are trapped by electron-deficient olefins. The coupling reactions of alkyl halides, described in Part I[1], are extended and, in addition, aryl halides are shown to be efficient radical precursors to yield coupling products in good yield.
    Additional Material: 2 Tab.
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    Solvolysis of Tricyclo[3.1.0.02,6]hex-3-yl and Bicyclo[2.1.1]hex-2-yl SulfonatesPresented at the third Euchem Symposium on Organic Reactivity, Goteborg, Sweden, July 1991.Dedicated to Professor John D. Roberts on the occasion of his 75th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1749-1757 
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    ISSN: 0009-2940
    Keywords: Bicyclo[1.1.0]butylcarbinyl sulfonates, solvolysis of ; Cyclobutylcarbinyl sulfonates, solvolysis of ; Anchimeric assistance in solvolysis ; Rearrangement of carbocations ; Electron demand in ditosylates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvolyses of cis-tricyclo[3.1.0.02,6]hex-3,4-diyl ditosylate (12) and cis-bicyclo[2.1.1]hex-2,3-diyl ditosylate (27) have been carried out in 80% aqueous ethanol in the presence of ethyl-diisopropylamine. In the former case, endo,endo-tricyclo[2.2.0.02,6]hexane-3,5-diol (13a), its monoether 13b and diether 13c were products whereas in the latter the monoethers 28b, d, e, g and the diethers 28a, c, f of bicyclo[3.1.0]hexane were formed. In pure ethanol, 12 was converted into pure 13c in good yield. In the presence of the weaker base 2,6-lutidine, the solvolysis of 12 in aqueous ethanol gave different products, i.e. exo,exo-4,6-diethoxybicyclo[3.1.0]hex-2-ene (14a) and several aldehydes, inter alia cyclopentadiene-1-carboxaldehyde (15). In control experiments, the tricyclic compounds 13b, c were converted into 14a, 15 and further aldehydes as well as into the bicyclo[2.1.1]hexene derivatives 19a, b. Sulfonates of tricyclo[3.1.0.02,6]hexan-3-ol (21a) could not be isolated but its mesylate 21c was characterized by NMR spectroscopy and hydrolysed in aqueous acetone to give tricyclo[2.2.0.02,6]hexan-endo-3-ol (22a). It is concluded from these results that the dissociations of the above sulfonates do not lead to unrearranged carbocations. Rather, they proceed with participation of the β-carbon in trans position relative to the leaving group resulting in the immediate generation of rearranged cations.-Kinetic studies show that the tricyclic mesylate 21c solvolyses in 80% ethanol/water 1.4 · 105 times as fast as bicyclo[2.1.1]hex-2-yl tosylate (25), and the tricyclic ditosylate 12 solvolyses 6 · 105 as fast as the corresponding bicyclic ditosylate 27. These rate enhancements are similar to those previously observed for less strained cyclopropylcarbinyl substrates.
    Additional Material: 6 Tab.
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    Chemie des η1-Rhenium-koordinierten Triphenylcyclopropenyl-Liganden (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1769-1779 
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    ISSN: 0009-2940
    Keywords: Rhenium complexes ; Cyclopropenyl, triphenyl-, complexes ; Propenyl, triphenyl-, complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of the η1-Rhenium-Coordinated Triphenylcyclopropenyl LigandThe s̰-coordinated pentacarbonyl[η1-1,2,3-triphenylcyclopropenyl)rhenium complex 1 is transformed into the green tetracarbonyl(η2-1,2,3-triphenylpropenetriyl)rhenium compound 2 with loss of CO by heating or irradiation. In addition, tetracarbonyl(η3-4-oxo-1,2,3-triphenylcyclobutenyl)rhenium (3a) and Tricarbonyl(η5-1,2,3,4,5,6-hexaphenylcyclohexadienyl)-rhenium (4) were obtained from this reaction. Treatment of 1 with trimethylamine N-oxide leads under oxygen transfer to tetracarbonyl(η2-3-oxo-1,2,3-triphenyl-1-propenyl)rhenium (5) and tricarbonyl(trimethylamine)(η2-3-oxo-1,2,3-triphenyl-1-propenyl)rhenium (6). The NMe3 ligand in 6 can be substituted either by CO or trimethyl phosphite to yield 5 or tricarbonyl-(trimethyl phosphite)(η2-oxo-1,2,3-triphenyl-1-propenyl)-rhenium (7), respectively. Complex 1 reacts with trimethyl-phosphane or trimethyl phosphite to give tetracarbonyl(phosphorus donor)(η1-4-oxo-1,2,3-triphenyl-2-cyclobuten-1-yl)rhenium 8b [L = PMe3] or 8c [L = P(OMe)3]. The derivatives Re(CO)3L2-η1-C3Ph3CO [L = CO, 8a; L = PMe3, 8d; L = P(O-Me)3 8e] were obtained by treatment of 3a with CO or two equivalents of PMe3 or P(OMe)3. The formation of 8d and 8e proceeded via the tricarbonyl(phosphorus donor)(η3-4-oxo-1,2,3-triphenylcyclobutenyl)rhenium compounds 3b and 3c. The unusual η1-coordination of the cyclobutenone system in 8 was established by an X-ray structure analysis of 8c. Furthermore, 4 and 5 were characterized by single-crystal X-ray diffraction. Reactions of 2 with alkynes led to substituted tricarbonyl(cyclopentadienyl)rhenium derivatives Re(η5-C5Ph3RR')(CO)3 9 (R = R' = Ph, 9a; R = R' = CO2Me, 9b; R = R' = CO2Et, 9c; R = Ph, R' = H, 9d).
    Additional Material: 3 Ill.
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    Reaktionen der Borhydride B3H7 und B5H9 mit den ungesättigten Bor-Stickstoff-Verbindungen NBtBu2 und NB2tBu3 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1787-1790 
    Details
    ISSN: 0009-2940
    Keywords: Iminoboranes ; Azadiboriridines ; Diaza-arachno-octaborane ; arachno-Nonaborate(1 -) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of the Boron Hydrides B3H7 and B5H9 with the Unsaturated Boron-Nitrogen Compounds NBtBu2 and NB2tBu3THF · B3H7 reacts with RB≡NR (1, R = tBu) to yield the μ-amino-diborane(6) B2H4R(NHR) (5), which crystallizes in the triclinic space group Pī. The reaction of B3H7 with the azadiboriridine NB2tBu3 (2, R = tBu) leads to the known NB2R3 · BH3 (4) and the novel (NB2R3)2B2H4 (6). Product 6 is considered to represent a diaza-arachno-octaborane derivative. The iminoborane 1 reacts with B5H9 in the presence of lutidine (L) to give the ionic product [L - BR = NHR][B9H14] (7); our earlier report on the formation of the aza-arachno-heptaborate [LH][NB6H8R2] has to be revised. The products from the reaction of B5H9 with NB2R3 are 4 and 6.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260805
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    Koordinationschemie Perhalogenierter Cyclopentadine und Alkine, XV. Systematischer Aufbau von fünffach ringsilylierten Cyclopentadienyl-mangan-Komplexen aus [C5Br5]Mn(CO)3. Molekülstruktur von [C5Br3(SiMe3)2]Mn(CO)3 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1791-1795 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienyls, highly silylated ; Cymantrenes, silyl- ; Pentakis(trimethylsilyl)cyclopentadienyl complex ; Manganese complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination Chemistry of Perhalogenated Cyclopentadienes and Alkynes, XV[1]. - Systematic Generation of Fivefold Ring-Silylated Cyclopentadienyl Manganese Complexes from [C5Br5]Mn(CO)3. Molecular Structure of [C5Br3(SiMe3)2]Mn(CO)3[C5Br5]Mn(CO)3 reacts in a sequence of alternate bromine-lithium exchange reactions and electrophilic silylations by SiMe3Cl or SiMe3OSO2CF3 to give [C5Br5-n(SiMe3)n]Mn(CO)3, where n = 1 (1), 2 (2), or 3 (3). A crystal structure determination of 2 shows the two silyl substituents in the relative 1,3-orientation. Addition of one or two equivalents of BuLi and SiMe2HCl to a solution of 3 yields [C5Br2-n(SiMe3)3-(SiMe2H)n]Mn(CO)3 with n = 1 (4) and 2 (5), respectively. If 1 is treated twice with 2 eq. of BuLi and then 2 eq. of SiMe2HCl, a further pentasilylated compound, [C5(SiMe3)(SiMe2H)4]-Mn(CO)3 (6), is obtained. In situ chlorination of [C5(SiMe2H)5]Mn(CO)3 or 6 with PdCl2, followed by addition of MeMgCl, yields after chromatography an inseparable mixture of [C5(SiMe3)4X]Mn(CO)3 compounds, where X = H (7a), SiMe2H (7b), and SiMe3 (7c).
    Additional Material: 1 Ill.
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    Gasphasenthermolyse von Pyrazolinen, 3[1]. Elektronische Struktur und Gasphasenpyrolyse von 4-substituierten 3,5,5-Trialkyl-3,5-dihydro-4H-1,2,3-triazolen untersucht durch Photoelektronenspektroskopie und semiempirische Rechnungen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2683-2689 
    Details
    ISSN: 0009-2940
    Keywords: Electronic structure ; Photoelectron spectroscopy ; Gas-phase thermolysis ; Pyrolysis ; 4H-1,2,3-Triazoles, 3,5-dihydro- ; Semiempirical MO calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas-Phase Thermolysis of Pyrazolines, 3[1]. - Electronic Structure and Gas-Phase Pyrolysis of 4-Substituted 3,5,5-Trialkyl-3,5-dihydro-4H-1,2,3-triazoles Studied by Photoelectron Spectroscopy and Semiempirical CalculationsThe PE spectra of the 3,5-dihydro-4H-1,2,3-triazoles 1-3 have been recorded. The ionization potentials have been assigned to molecular orbitals on the basis of MNDO, AM1, and PM3 calculations. The most important occupied MOs are characterized as πNNN, πC=X (X = O, NCH3, CH2), nN-3, nNN+, nNN- and nX. The gas-phase thermolyses of 1-3 have been studied by PE-controlled real-time gas analysis. After extrusion of molecular nitrogen, the remaining reactive species cyclize to three-membered rings. At higher temperatures and in flash vacuum pyrolysis, subsequent reactions lead to smaller acyclic compounds.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261218
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    Synthese mittlerer und großer Ringe, XXXV[1]. Funktionalisierte Hydroazulenone durch transannulare Cyclisierungen von 10-Oxo-3,6-hexanooxepin-4,5-dicarbonsäure-dimethylester (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2691-2696 
    Details
    ISSN: 0009-2940
    Keywords: Azulenones, cis-octa- and decahydro- ; Stereoselective cyclization ; Hydrogenation ; Oxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Medium and Large Rings, XXXV[1]. - Functionalized Hydroazulenones by Transannular Cyclizations of Dimethyl 10-Oxo-3,6-hexanooxepine-4,5-dicarboxylateTwo differently bridged hydroazulenones 2 and 3 are obtained in 69 and 61% yield, respectively, by treatment of the title compound 1 with sodium methoxide. The course of these intramolecular transannular cyclizations strongly depends on the amount of added base. 2 is hydrogenated to the ketones 9 and 10. Oxidative cleavage of the enol ether double bond of 3 and 10 leads to the octahydroazulene-1,6-dione 11 and to the decahydroazulene-3,8-dione 12, respectively.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261219
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    Dihydroselenapyrans by [4 + 2] Cycloaddition of Diaryl Selenoketones (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1895-1903 
    Details
    ISSN: 0009-2940
    Keywords: Selenoketones ; Selenapyrans, dihydro ; Staudinger chalcogenation ; Phosphorus ylides ; Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The phosphorus ylides Ph3P=CAr1Ar2 5 [Ar1 = Ph, Ar2 = 4-CH3C6H4 (c); Ar1 = Ar2 = Ph (d); 4-ClC6H4 (e); 4-FC6H4 (f); 3-CF3C6H4 (g); Ar1 = Ph, Ar2 = 4-ClC6H4 (h)] were allowed to react with elemental selenium at ca. 75°C in toluene in the presence of an excess of 2,3-dimethylbutadiene. The diaryl selenoketones 1 thus generated in situ by means of the „Staudinger chalcogenation“ reaction were trapped by the added conjugated diene to give the 2,2-diaryl-3,6-dihydro-4,5-dimethyl-2H-selenapyrans 7 in high yield. Similarly, the ylides 5c-f and 5h were treated with selenium, and the resulting diaryl selenoketones 1 added to 1,3-butadiene to give the corresponding 2,2-diaryl-3,6-dihydro-2H-selenapyrans 8. Selenobenzophenone, synthesized analogously, was employed in a [4 + 2] cycloaddition reaction with 2,3-dimethoxybutadiene to yield 3,6-dihydro-4,5-dimethoxy-2,2-diphenyl-2H-selenapyran (9), which was characterized by an X-ray crystal structure analysis. Compound 9 crystallizes in the space group P21/n. In the crystal the dihydro-2H-selenapyran adopts a distorted half-chair conformation.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260821
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    LiClO4-katalysierte nucleophile Addition an α-chirale Aldehyde, Aldimine und OxiraneHerrn Professor Reinhard W. Hoffmann zum 60. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1905-1912 
    Details
    ISSN: 0009-2940
    Keywords: Ketene acetals, O-silylated ; Aldehydes, α-alkoxy ; α-Amino aldehydes ; Mukaiyama aldol reactions ; Cyanhydrines ; Aldimines ; β-Amino esters ; Diastereoselektivity ; Oxiranes ; Ring opening ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: LiClO4-Catalyzed Nucleophilic Addition to α-Chiral Aldehydes, Aldimines, and OxiranesThe diastereoselectivity of lithium perchlorate-induced addition of trimethylsilyl cyanide and O-silylated ketene acetals to α-chiral aldehydes is studied. Whereas aldehyde 1 reacts with the ketene acetal 2 exclusively to form the syn-ester 3, a divergent selectivity is observed in the case of trimethylsilyl cyanide addition to 5 and 11a-c. Also the reaction of O-silylated ketene acetals with aldimines 16 in the presence of lithium perchlorate proceeds smoothly to afford the corresponding β-amino esters 17 in high yields. While the silyl ketene acetal of methyl acetate leads preferentially to the corresponding anti-diastereomer, in the case of the silyl ketene acetal of methyl isobutyrate a syn-/anti-selectivity in the range of 79:21 to 44:56 is observed. In the presence of lithium perchlorate solution in ether the oxiranes 27a-d undergo facile nucleophilic ring opening reactions with 2, 29, and 30.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931260822
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    A Stepwise [4 + 3] Cycloaddition Reaction of the 1,3-Diphenyl-2-azaallyl AnionDedicated to Professor R. W. Hoffmann on the occasion of his 60th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1913-1916 
    Details
    ISSN: 0009-2940
    Keywords: 2-Azaallyl anion, 1,3-diphenyl ; [4 + 3] Cycloaddition ; Concertedness ; Pyrrolidines ; Azepine, tetrahydro- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1,3-diphenyl-2-azaallyl anion (1) undergoes [3 + 2] cycloaddition reactions with the s-cis-fixed 1,3-dienes 8-11. In contrast, 1,1,2,2,3,3-hexamethyl-4,5-bis(methylene)cyclopentane (7) reacts with 1 to give the [4 + 3] cycloadduct 13 and the linear 1,4-addition product 14. This reaction is four orders of magnitude slower than the corresponding reaction of 1 with 1,2-bis(methylene)cyclopentane (8), which exclusively yields [3 + 2] cycloadducts. A change of mechanism - concerted cycloaddition of 8 and stepwise cycloaddition of 7 - is suggested, but not unequivocally proven. It is concluded that reactions of 1 with ordinary dienes cannot profit from concertedness by more than 5 kcal · mol-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260823
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    Diastereo- und enantioselektive Synthese 1,2-trans-substituierter Cycloalkancarbonsäureester und Sulfone durch Michael-initiierte Cyclisierungen via SAMP-/RAMP-Hydrazone[1,2] (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1929-1944 
    Details
    ISSN: 0009-2940
    Keywords: SAMP Hydrazones ; RAMP Hydrazones ; MIRC reactions ; Cycloalkanecarboxyl acid esters ; Sulfones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diastereo- and Enantioselective Synthesis of 1,2-trans-substituted Cycloalkanecarboxylates and Sulfones by Michael-Initiated Cyclisation via SAMP / RAMP Hydrazones[1,2]An efficient and flexible synthesis of 1,2-trans-substituted cycloalkanecarboxylates and sulfones of high diastereo- and enantiomeric purity is described. The key step of the procedure is a Michael-initiated ring closure (MIRC) reaction employing the SAMP/RAMP hydrazone method. Depending on the chain length of the ω-bromo(iodo)enoates 2, 3 and the type of ketone SAMP-hydrazone 1, 3-, 5-, 6- and 7-membered cycloalkane-carboxylates 4-7 or cyclopentanesulfones 24 bearing two or three stereogenic centers are formed with very high asymmetric induction. In the same manner, MIRC reactions with ω-(ethoxycarbonyl)enoate 26 give rise to 3-substituted cyclopentanone-2-carboxylates 27, but with lower overall chemical yields. The relative and absolute configurations are based on X-ray structure analyses, spectroscopic and mechanistic investigations.
    Additional Material: 9 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931260825
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    Mass-Spectrometric and GAUSSIAN2 Studies of the Diazene (HNNH) and Isodiazene (H2NN) Molecules and Their Radical CationsDedicated to Professor Werner Schroth on the occasion of his 65th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2753-2758 
    Details
    ISSN: 0009-2940
    Keywords: Charge-transfer experiments ; Tandem mass spectrometry ; Diazene ; Potential energy surface ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collision experiments demonstrate that isodiazene (H2NN) and its radical cation are viable molecules in the gas phase. The mass-spectrometric experiments are complemented by extensive ab-initio MO calculations using the GAUSSIAN-2 procedure in order to map out relevant parts of the potential energy surface of H2N2 (singlet) and H2N2+· (doublet).
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261227
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    Umlagerungsreaktionen von Metallodiphosphapropenen des Typs (η5-C5Me5)(CO)2FeP(SiMe3)  -  P = C(R)(SiMe3) (R = SiMe3, Ph)Herrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1963-1968 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphapropenes ; CH insertion ; Diphosphiranes ; Chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of the Metallodiphosphapropenes (η5-C5Me5)(CO)2FeP(SiMe3  -  P = C(R)(SiMe3) (R = SiMe3, Ph)Heating of a methylcyclohexane solution of (η5-C5Me5)-(CO)2FeP(SiMe3)  -  P = C(SiMe3)2 (1a) gives rise to the insertion of the P = C moiety into the CH bond of a ring methyl group with formation of the chelate complex η5-ηC5Me4CH2P-[CH(SiMe3)2]P(SiMe3)Fe(CO)2 (2) which is converted into the pentacarbonylchromium derivative [5-C5Me4CH2P[CH-(SiMe3)2]P(SiMe3)[Cr(CO)5]Fe(CO)2] (3). In contrast, a similar treatment of (5-C5Me5)(CO)2FeP(SiMe3)  -  P = C(Ph)(SiMe3) (1 b) furnishes the diphosphirane (5-C5Me5)(CO)2FeP  -  C(Ph)-SiMe3)  -  P (SiMe3) (5). By chromatography of its (CO)5Cr adduct 6, the P  -  Si bond is hydrolyzed to give the (diphosphirane)-chromium complex [(5-C5Me5)(CO)2FeP-C(Ph)(SiMe3)P(H)]-Cr(CO)5 (8). The molecular structures of 3 and 8 are determined by single-crystal X-ray analysis.
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    1,1-Organoboration of Di-1-alkynylsilanes with Alkynyl Groups of Different Reactivity: New Organometallic-Substituted Siloles (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2221-2226 
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    ISSN: 0009-2940
    Keywords: Silanes, alkynyl[(trimethylstannyl)ethynyl]- ; 1,1-Ethyloboration, intermolecular ; 1,1-Vinyloboration, intramolecular ; Siloles ; Protodeborylation ; Protodestannylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of alkynyl[(trimethylstannyl)ethynyl]dimethylsilanes 4 [alkynyl R1 - C≡C: R1 = Bu (b), tBu (c), iPent (d), Ph (e), SiMe3 (f)] is reported. The intermolecular 1,1-ethyloboration of 4 with triethylborane takes place selectively at the Sn - C≡ bond to give first the alkenyl(alkynyl)dimethylsilanes 5 and 6. There exists an equilibrium between 5 and 6, and compound 6 has the suitable stereochemistry for the final intramolecular 1,1-vinyloboration to form the 4-(diethylboryl)-2-(trimethylstannyl)siloles 7. Protodeborylation of 7 with water gives the 2-(trimethylstannyl)siloles 8, and protodeborylation and protodestannylation with an excess of acetylacetone affords the siloles 9. Multinuclear NMR (1H-, 11B-, 13C-, 29Si-, and 119Sn-) serves for monitoring the reactions and for the characterization of the products.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261009
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    Neue Wege zu Bis[(cyclopentadienyl)cobalt]-μ-(η5-2,3-dihydro-1,3-diborolyl)-Tripeldeckerkomplexen über Wasserstoff-Verschiebungsreaktionen in Derivaten des 4,5-Diisopropyliden-1,3-diborolans, des 2,4,5-Triisopropyliden-1,3-diborolans und des Benzo-1,3-diborafulvensHerrn Professor Dr. Wolfgang Sundermeyer zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2197-2203 
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    ISSN: 0009-2940
    Keywords: 1,3-Diborolyl complexes, bis[η5-cyclopentadienyl)cobalt] ; 1,3-Diborolane, 4,5-diisopropylidene- and 2,4,5-triisopropylidene- ; Benzo-1,3-diborafulvene ; Electrochemistry ; ESR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Routes to Bis[(cyclopentadienyl)cobalt]-μ-(η5-2,3-dihydro-1,3-diborolyl) Triple-Decker Complexes by Hydrogen Shift Reactions in Derivatives of 4,5-Diisopropylidene-1,3-diborolane, 2,4,5-Triisopropylidene-1,3-diborolane, and Benzo-1,3-diborafulveneThe 31 VE dicobalt triple-decker complexes 6, 7a, 7b, c, 8a, b, and 9a, b with bridging 2,3-dihydro-1,3-diborolyl ligands are prepared. The reaction of the 1,3-diborole 1 with [(C5Me5)-Co(C2H4)2] leads to the sandwich complex 5, which is treated with [(C5H5)Co(C2H4)2] to yield unsymmetrical 6. The 4,5-diisopropylidenetrimethyl-1,3-diborolane 3 undergoes a metal-induced 1,5-hydrogen shift and reacts with [(C5H5)Co(C2H4)2] to form the triple-decker 7a. The reaction of the 2,4,5-triisopropylidene-1,3-diborolane 4 with [(C5H5)Co(C2H4)2] leads to a mixture of the triple-deckers 7b/c, formed by intermolecular hydrogen shift. The benzo-1,3-diborafulvene derivatives 2b and 2c also react with [(C5H5)Co(C2H4)2] to give the triple-decker 8b and a mixture of 9a, b. In addition, the trinuclear complex 8c is obtained in low yield. The new paramagnetic triple-decker complexes have been analyzed by NMR and ESR spectroscopic measurements as well as by electochemistry. The constitutions of 7b/c, 8b, 8c, and 9a/b have been confirmed by X-ray structure analyses. The complexes are iso-structural, the Co - Co distances range from 3.277(1) (7b/c) to 3.316(1) Å for 8c.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931261006
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    Synthese, Reaktivität und Komplexeigenschaften von nido-2,3,5-TricarbahexaboranenHerrn Professor Hans Bock zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2205-2210 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Dihydro-1,3-diborafulvenes ; 4,5-Dimethylidene-1,3-diborolanes ; Hydroboration ; nido-2,3,5-Tricarbahexaboranes ; Metal complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, Reactivity and Complexation Properties of nido-2,3,5-TricarbahexaboranesBy double hydroboration of 1,3-dihydro-1,3-diborafulvenes 2 or 4,5-diisopropylidene-1,3-diborolanes 3 with (Et2BH)2 and subsequent loss of triethylborane derivatives 1 of 2,3,5-tricarbahexaborane are formed under mild conditions. The stability of the nido-carboranes 1 depends on the substituents in the basal positions. After deprotonation, the tricarbahexaboranate ion (1  -  H) -  functions as a cyclopentadienyl analogue (C5H5) - , and its reaction with allylnickel bromide dimer gives the allylnickel complexes 8a, b. Reaction of octacarbonyl dicobalt with 1b yields the dicarbonylcobalt complex 10b. Treatment of 1e with [(C5H5)Ni(CO)]2 results in the formation of the di-nuclear carbonyl-bridged complex 12e.
    Additional Material: 2 Tab.
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    Strukturen und Moleküleigenschaften sterisch überfüllter Moleküle, 36. (E)-1,1,1,4,4,4-Hexakis(trimethylsilyl)-2-buten [(H3C)3Si]3C - HC=CH - C[Si(CH3)3]3 und Bis[tris(trimethylsilyl)silyl]ethin [(H3C)3Si]3Si - C≡C - Si[Si(CH3)3]3 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2227-2235 
    Details
    ISSN: 0009-2940
    Keywords: Silicon compounds ; Sterically overcrowded organosilicon molecules ; Photoelectron and ESR spectra of radical cations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structures and Molecular Properties of Sterically Overcrowded Molecules, 36[1].  -  (E)-1,1,1,4,4,4-Hexakis(trimethylsilyl)-2-butene [(H3C)3Si]3C - HC=CH - C[Si(CH3)3]3 and Bis[tris(trimethylsilyl)silyl]ethin [(H3C)3Si]3Si - C≡C - Si[Si(CH3)3]3The single crystal structure of an ethylene derivative, in which the two substituent half-shells are separated by a C=C spacer of about 403 pm length, shows C≡C distances of 404, 415 as well as 421 pm between non-adjacent and of 352 pm between adjacent methyl groups, i.e. close to or within their van der Waals radii sum of 400 pm. The PE-spectroscopically determined vertical first ionization energies of both compounds, 7.78 eV and 7.71 eV, are each the lowest ones reported so far for disubstituted ethylenes and acetylenes. Despite of irreversible cyclovoltammetric oxidation potentials, the radical cation of the six-fold R3Si-substituted 2-butene can be generated by SbCl5/H2CCl2 and characterized below 230 K by its ESR spectrum.
    Additional Material: 4 Ill.
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    Strukturen und Moleküleigenschaften sterisch überfüllter Moleküle, 37. Hexakis(trimethylsilylmethyl)benzol C6[CH2Si(CH3)3]6 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2237-2241 
    Details
    ISSN: 0009-2940
    Keywords: Sterically overcrowded organosilicon molecules ; Radical cation dynamics ; Silicon compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structures and Molecular Properties of Sterically Overcrowded Molecules, 37[1].  -  Hexakis(trimethylsilylmethyl)benzene C6[CH2Si(CH3)3]6Both the low first vertical ionization energy of only 7.40 eV, determined by PE spectroscopy for C6[CH2Si(CH3)3]6, and the blocked substituent rotation in its radical cation as proven by ESR/ENDOR spectroscopy suggest considerable steric over-crowdedness. To further substantiate this interpretation of the molecular properties, the crystal structure (hexagonal R3, Z = 2) has been determined at 100 K. Accordingly, the bulky trimethylsilyl groups are arranged alternatingly above or below the C6-ring plane, out of which the methylene C centers are twisted by ±9°. Due to the angles CCSi widened to 115°, however, the intramolecular distances C(H)=(H)C between non-neighboured methyl groups of 443 and 452 pm even slightly exceed their van der Waals radii sum of 400 pm and thus avoid severe spatial congestion.
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    Chemie der Isoblausäure, 9. Dreikomponenten-Cycloadditionen mit CyanokomplexenHerrn Professor Dr. Dr. mult. Hans Bock zum 65. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2243-2246 
    Details
    ISSN: 0009-2940
    Keywords: Reactions at coordinated cyanide ; Cycloadditions, organometallic ; Carbenoid heterocycles ; Metal-ligand bond cleavage ; Oxazolinone syntheses ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of Hydrogen Isocyanide, 9[1].  -  Three-Component Cycloadditions with Cyano ComplexesA novel and obviously general reaction of the coordinated cyano ligand in [M(CN)(CO)5] -  (M = Cr, W) is reported, viz. its high-yield one-step [2 + 1 + 2] cycloaddition with a great variety of isocyanides and ketones resulting in carbenoid metal complexes of five-membered N,O heterocycles. The structure of the product 1a from [W(CN)(CO)5] - , tert-butyl isocyanide, and diethyl ketone has been elucidated by X-ray diffraction and found to contain a C-bound non-aromatic 4-aminooxazoline with an unprecedented π-delocalization along the exo chain which is also evident from severe low-field shifts of the C-2 and C-4 signals in the 13C-NMR spectra. The heterocycles are cleaved off the metal by oxidative decomposition with KMnO4/Fe(NO3)3 to give the corresponding oxazolinones, e.g. 4, with a high potential for biological activity. The general validity of this reactivity pattern for metal cyanides is further demonstrated by the successful incorporation of cyanoiron(II) and -cobalt(III) species in these three-component cycloaddition reactions.
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    Reaktionen eines freien Stannaimins und von Basen-stabilisierten Stannylenen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2247-2253 
    Details
    ISSN: 0009-2940
    Keywords: Stannaimine ; Stannylenes ; 1,2-Additions ; [2 + 2] Cycloadditions ; [2 + 3] Cycloaddition ; [2 + 4] Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of a Free Stannaimine and of Base-Stabilized StannylenesThe free stannaimine A reacts with methyllithium, 2,6-diisopropylaniline, and methyl vinyl ketone to give the corresponding 1,2-addition products (to the Sn—N bond) 2, 3, and 10. With 2,6-diisopropylphenyl isocyanate and benzaldehyde [2 + 2] cycloadditions to the C=O bonds lead to 4 and 5, while with benzonitrile oxide and acroleine [2 + 3] and [2 + 4] cyclo-additions produce 8 and 9. The pyridine adducts bis-[bis(trimethylsilyl)amino]stannylene and -germylene react with aryl azides to give the corresponding derivatives of tri-amino-2-pyridylstannane 11 and -germane 12. Bis[2-pyridyl-bis(trimethylsilyl)methyl]stannylene upon treatment with aryl azides form the 1-aza-8-stannabicyclo[3.2.0]octa-2,4,6-triene systems 13 and 14 via stannaimine intermediates. X-ray structure analyses are presented for 3, 11, and 13.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931261013
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    New Organophosphorus Ligands: 1,1,2-Tris(diphenylphosphanyl)cyclopropane and Its Derivatives (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2259-2261 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopropane, phosphanyl-substituted ; Phosphane ligands ; Phosphane oxide and sulfide ; Phosphane - borane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclopropanation of 1,1,2-tris(diphenylphosphanyl)ethene with dimethylsulfonium methylide affords the title compound 1. The trifunctional phosphane is transformed into the trioxide 2 and trisulfide 3 by oxidation with hydrogen peroxide or elemental sulfur, respectively. With the tetrahydrofuran  -  borane complex the tris(phosphane - borane) 4 is obtained. The crystal structure of compound 1 has been determined by single-crystal X-ray diffraction.
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    Chemoselectivity in Catalytic Transfer Hydrogenation  -  Reduction of Alkenes and Alkynes with the H2PO2 - NH4+ · H2O/Pd-C System (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2265-2268 
    Details
    ISSN: 0009-2940
    Keywords: Chemoselectivity ; Protonolysis ; Transfer hydrogenation ; Alkenes, reduction of ; Alkynes, reduction of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The H2PO2 - NH4+ · H2O/Pd-C system acts as an unusually powerful reducing agent, which is able to reduce cyclooctene to cyclooctane, Δ9,10-octalin to decalins, α- and β-pinenes to pinanes at room temperature in high yield without the formation of byproducts. This system selectively reduces each of these compounds or partly (alkynes to alkenes), depending on the competition between the transfer hydrogenation to give alkanes and the protonolysis to give hydrogen gas on the palladium catalyst.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931261016
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    Preparative, X-ray, and NMR Studies of the Interaction of Beryllium with Salicylic and o-Cresotic Acid: Crystal Structures of (NH4)2[Be(C6H4OCO2)2] · 2.25 H2O and Na3[Be(C7H6OCO2)(OH)(CO3)Be(C7H6OCO2)] · 8 H2O (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 3-9 
    Details
    ISSN: 0009-2940
    Keywords: Salicylic acid ; o-Cresotic acid ; Beryllium, toxicity of ; 9Be NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The existence of well-defined crystalline beryllium salicylate(2 - ) and bis[salicylato(2 - )]beryllate complexes as well as of their o-cresotate analogs is established. The structure of (NH4)2[Be(C6H4OCO2)2] · 2.25 H2O has been determined by an X-ray structure analysis. It contains a beryllate anion of the composition [Be(C6H4OCO2)2]2- with two salicylate(2 - ) ligands acting as chelate ligands. The considerable 9Be NMR chemical shifts observed for aqueous solutions of the pure compounds indicate in all cases the persistence of the complexation of the metal ion by the catecholate ligands. 9Be NMR studies of aqueous solutions containing BeSO4 · 4 H2O and sodium salicylate(1 - ) or sodium o-cresotate(1 - ) in the molar ratios 1:1 and 1:2 show that a variety of beryllium/salicylate(2 - ) and beryllium/o-cresotate(2 - ) species are present in solution, the most prominent being Be(C6H4OCO2)-(H2O)2 and [Be(C6H4OCO2)2]2- (and their o-cresotate analogs). From such solutions in contact with air, a novel dinuclear beryllium hydroxido/o-cresotato(2 - )/carbonato complex of the stoichiometry Na3[Be2(OH)(CO3)(C7H6OCO2)2] · 8 H2O is isolated. According to an X-ray analysis the compound contains a cyclic beryllate anion with two Be(C7H6OCO2) chelate units linked by bridging hydroxide and carbonate anions. In the light of the ubiquitous availability of phenolic and carboxylic groups in many biomolecules, the finding of strong bonding of Be2+ to these functions in aqueous solution is very important.
    Additional Material: 5 Ill.
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    Preparation of 3,4,5-Trisubstituted 1,2,4-Oxadiazolium Salts from Nitrilium Salts (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 109-116 
    Details
    ISSN: 0009-2940
    Keywords: Nitrilium salts ; Nitrile oxides ; N-Hydroxycarboximidoyl chlorides ; 1,2,4-Oxadiazolium salts ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Cycloadditions of stable nitrile oxides 2 to nitrilium salts 1 afford high yields of 3,4,5-trisubstituted 1,2,4-oxadiazolium salts 3. N-Hydroxycarboximidoyl chlorides 4 add to nitrilium salts 1 to give isolable [(chloroalkylidene)aminooxyalkylidene]ammonium salts 5. A thermal stereomutation around the C = N+ bond is observed. On heating neat or in solution most compounds 5 cyclize to oxadiazolium salts 3. In cases where decomposition of 5 is faster than cyclization O-silylated N-hydroxycarboximidoyl chlorides 7 are treated with nitrilium salts 1 to furnish oxadiazolium salts 3.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19931260118
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    3-Azabicyclische Ketone durch Reaktionen von 1,3-Diethoxy-2-azapropenylium-Salzen mit Enaminen cyclischer Ketone (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 133-141 
    Details
    ISSN: 0009-2940
    Keywords: 2-Azapropenylium salts ; Enamines ; 3-Azabicyclo[3.2.1]oct-2-en-8-ones ; 3-Azabicyclo[3.3.1]non-2-en-9-ones ; Stereochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Azabicyclic Ketones from 1,3-Dialkoxy-2-azapropenylium Salts and Enamines of Cyclic Ketones1,3-Diethoxy-2-azapropenylium salts 1 are powerful biselectrophiles and react diastereoselectively with enamines of five-membered ring ketones 2 to yield novel 3-azabicyclo[3.2.1]oct-2-en-8-one 5 after hydrolysis of the intermediate iminium salts 3, 4. Some of the iminium salts 3 can be hydrolyzed further to provide the diketo imines 6. With enamines of six-membered ring ketones 7 the 3-azabicyclo[3.3.1]non-2-en-9-ones 10, 11 are obtained after hydrolytic workup. Mixtures of diastereomers 10/11 are found in the case of 7a, b, whereas with 7g  -  j the endo-phenyl derivatives 10 are formed exclusively. With the unsymmetrical enamine 7b only one regioisomer is observed. The decalone enamine 12 reacts with 1a to yield the tricyclic iminium salt 13.  -  The configuration of the bicyclic products has been determined by using NMR spectroscopic techniques (COSY, polarisation transfer by long range couplings); an X-;Ray analysis of compound 10a is used as basis for the NMR assignments. General rules for the determination of the stereochemistry of these azabicyclic systems by 1H-NMR shift arguments are derived.
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    URL: http://dx.doi.org/10.1002/cber.19931260121
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    Metallkomplexe mit biologisch wichtigen Liganden, LXVII[1]. Synthese von α-Aminosäuren aus Palladium(II)- und Rhodium(III)-koordinierten Iminen und Oximen von α-OxocarboxylatenHerrn Professor Dr. Wolfgang Steglich zum 60. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2421-2427 
    Details
    ISSN: 0009-2940
    Keywords: Palladium complexes ; Rhodium complexes ; α-Amino acids ; 2-Iminocarboxylate as ligand ; Chiral glycine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LXVII[1]. - Synthesis of α-Amino Acids from Palladium(II)- and Rhodium(III)-Coordinated Imines and Oximes of α-OxocarboxylatesThe bis-chelate complexes Pd[O2CC(R1)=NOR2]2 (1) and Pd[O2CC(R1)=NR2]2 (2, R2 optically active substituent) are synthesized by template condensation of an α-oxocarboxylic acid with a hydroxylamine or amine component, respectively. Similarly, the Rh(III) complexes Cp*Rh(Cl)[O2CC(R)=N(CHMePh)] (3a: R = H, 3b: R = Me) were obtained from α-oxocarboxylic acids and optically active 1-phenylethylamine. Catalytic hydrogenation of 1 and 2 gives directly the free α-amino acids with, in case of 2, ee's between 0 and 36%. Nucleophilic attack by the carbanions of RC(O)CH2CO2Et and H2NCH(CO2Et)2 at the imino carbon atom of 3a leads to the α-amino carboxylato complexes 4 and 5. - Compounds 4a and 5 have been characterized by X-ray diffraction. Reaction of 3a with NaBH4 or NaBD4 followed by decomposition of the complex with HCl yields N-substituted glycine and N-substituted α-deuterio-glycine, respectively. The diastereoselectivity (70:30) of the α-deuteration could be determined by NMR spectroscopy.
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    Metallkomplexe mit biologisch wichtigen Liganden, LXVIII. Metallorganische Asparaginato-Cobaltkomplexe als Liganden für Alkali-Ionen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2429-2432 
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    ISSN: 0009-2940
    Keywords: Aspartic acid ; Asparagine ; Diamino carboxylic acid ; Cobalt complexes ; Alkali complexes ; Pentamethylcyclopentadienyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LXVIII[1]. - Organometallic Asparaginato Cobalt Complexes as Ligands for Alkaline IonsThe trischelate complexes of the dianion of aspartic acid and β-methylaspartic acid (η5-C5Me5)] (R = H, Me) form adducts with alkali iodides MI (M = Li, Na, K). The polymeric structure of (η5-C5Me5)Co(L-asp.-2H+)KI (1c) was determined by X-ray diffraction. In the crystal of 1c the potassium ions are surrounded by five oxygen atoms of the carboxylate groups whereby two oxygen atoms form bridges between two K+ ions. Similarly, trischelate complexes 4 and 5 have been obtained from (η5-C5Me5)Co(CO)I2 and 2,3-diaminopropionic, 2,4-diaminobutyric acid, and asparagine, respectively.
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    Reaktionen von (Fluorsulfonylimino)-λ6-schwefeltetrafluorid FSO2N=SF4Herrn Professor Pedro J. Aymonino zum 60. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2437-2439 
    Details
    ISSN: 0009-2940
    Keywords: Sulfur tetrafluoride imides ; Fluorosulfonylamines ; Pentafluorosulfanylamines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of (Fluorosulfonylimino)-λ6-sulfur Tetrafluoride FSO2N=SF4Herrn Professor Pedro J. Aymonino zum 60. Geburtstag gewidmet.FSO2N=SF4 (1) reacts with CsF, HF and CIF to form Cs+N(SO2F)SF5- (2), HN(SO2F)SF5 (3) and ClN(SO2F)(SF5) (5); 5 adds to ethylene to give ClCH2CH2N(SO2F)SF5 (6).
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    Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXXV. Konsekutive Insertions- und [2 + 2]-Cycloadditions-Reaktion von Hexafluor-2-butin mit einem (η2-Thiophosphinito)cobalt-Komplex (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2433-2435 
    Details
    ISSN: 0009-2940
    Keywords: Cobalt, (η2-thiophosphinito) and (η3-cyclobutenyl) complexes ; Alkyne insertion ; [2 + 2] Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties and Reactions, LXXXV[1]. - Consecutive Insertion and [2 + 2] Cycloaddition Reaction of Hexafluoro-2-butyne with an (η2-Thiophosphinito)cobalt complexInsertion of hexafluoro-2-butyne (2) into the Co - P bond of the (η2-thiosphosphinito)cobalt complex (OC)2Ph3PCo(η2-SPt2) (1) and subsequent [2 + 2] cycloaddition to a second alkyne 2 results in the formation of the stable (η3-cyclobutenyl)cobalt complex 3. According to an X-ray structural analysis 3 crystallizes in the triclinic space group P1 with Z = 2.
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    Alkylierungsreaktionen an 4,5-Bis(trifluormethyl)-1,3-dithiol-2-thion  -  Erste Röntgenstrukturanalyse eines 2-Alkylthio-1,3-dithiolium-Salzes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 273-275 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Dithiole-2-thione, 4,5-bis(trifluoromethyl)- ; Alkylation ; Perfluorobutanesulfonic acid, alkyl esters ; Triethyloxonium hexachloroantimonate ; 1,3-Dithiolium salts, 2-alkylthio- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation Reactions of 4,5-Bis(trifluoromethyl)-1,3-dithiole-2-thione  -  A First X-ray Structure Determination of a 2-Alkylthio-1,3-dithiolium SaltThe 2-alkylthio-1,3-dithiolium salts 2a  -  e have been prepared by reaction of 4,5-bis(trifluoromethyl)-1,3-dithiole-2-thione (1) with strong alkylating agents like alkyl perfluorobutanesulfonates or Meerwein salts. The first X-ray structure determination shows a localized double bond in the ring system combined with a trithiocarbenium ion in 2e.
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    URL: http://dx.doi.org/10.1002/cber.19931260138
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    Modellreaktionen zur Verankerung von Molybdän-und Vanadium-Oxiden auf Silicium-Sauerstoff-Oberflächen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 279-283 
    Details
    ISSN: 0009-2940
    Keywords: Molybdenum(VI) compound ; Siloxanes ; Vanadium(V) compound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Model Reactions to Anchor Molybdenum and Vanadium Oxides on Silica-Oxygen SurfacesThe eight-and twelve-membered ring compounds [(tBu)21-Si(O)2MoO2]2 (1) and [(tBu)2Si(O)2V(O)Cl]3 (2) have been prepared by the reaction of di-tert1-butylsilanediol or its dilithium salt with MoO2Br2 or VOCl3, respectively. Single crystal X-ray structure analyses of 1 · 2 py and 2 have been performed. Crystals of 1 · 2 py contain two molecules of 1 · 2 py and four additional molecules of pyridine in the unit cell.
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    Reaktionen von 1-Phenyl-3-borolenen mit Aldehyden, Ketonen und Ketenen: Synthese von 1,2-Oxaborolan-Derivaten, 2,3-anti-1,3-Diolen und ungesättigten β1-Hydroxyalkylketonen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 297-304 
    Details
    ISSN: 0009-2940
    Keywords: Diastereoselective synthesis ; Homoallylic alcohols ; 1,3-Diols, homoallylic ; β1-Hydroxyalkyl ketones ; 2,5-Dihydro-1H1-boroles ; 1,2-Oxaborolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Phenyl-3-borolenes CH2CR1=CR1CH2BPh) (1a: R1=H; b: R1=Me) react with aldehydes R2CHO to give cis-1,2-oxaborolanes CH2CR1[CR1(=CH2)]CR2R3OBPh (2, R2 = e.g. Me, Ph, CH=CH2, tBu, CCl3, R3 = H). Yields are nearly quantitative. Stereoselectivities usually are 100% (but only 95% for R2=CH=CH2, 97% for R2=Me). Oxidation with NaOH/H2O2 in THF affords homoallylic anti-1,3-diols HOCR2R31-CR1[CR1(=CH2)]CH2OH (3). An X-ray diffraction analysis of 3a (R2=p1-tolyl) proves the assigned stereochemistries. Ketones R2R3CO react analogously. Ketenes R2CCO form 5-alkylidene-4-vinyl-1,2-oxaborolanes (4), which tend to undergo double-bond migration. Oxidation produces two types of β1-hydroxylalkyl ketones R22CHCOC[(E)=CHMe]CH2OH (5) and R22CHCOCMe[CMe=CH2]CH2OH (6).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260205
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    Organosubstituierte cis-1,2-Diborylalkene als elektrophile Chelatbildner (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 305-317 
    Details
    ISSN: 0009-2940
    Keywords: cis-1,2-Diborylalkenes, electron acceptors, anion sponge ; Diborates, hexaorgano, μ1-hydro, μ1-alkoxy, alkali metal salts ; Borates, hydrotriorgano- ; Substituent exchange, diborates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organosubstituted cis-1,2-Diborylalkenes as Electrophilic ChelatesTriethylborane (1), 9-ethyl-9-borabicyclo[3.3.1]nonane (9-ethyl-9-BBN) (2), and the cis-1,2-diborylalkenes (Z)1-R2BC(R′)=C(Et)BEt2 [3: R=Et, R′=Me; 4: R,R′=Et; 5: R=Et, R′=Ph; 6: R2=C8H14, R′=Et; 7: R=Ph, R′=Et] react with alkali metal salts MX [M=Na, K; X=H, OMe, OtBu, OSiMe3, OSiEt3] in toluene to give the borates MX-1, MX-2, and the cyclic cis-1,2-diborates M, resp., [e.g. KH-3 to KH-7; NaOMe-4 to NaOMe-6; KOtBu-4, KOSiMe3-4, KOSiEt3-4] with BHB-and B(OR)B-bridges (IR, Multi NMR). Reaction of 1, 2, and 3-6 with KCN leads to the monoborates KCN-1, KCN-2, and to the acyclic cis-1,2-diborates KCN-3 to KCN-7.  -  The cis-2-Boryl-1-silylalkenes (E)1-Me3SiC(R′)=C(Et)BEt2 [8: R′=Me; 9: R′=Et] and KX [X=H, CN, OMe] form the acyclic borates K[Me3SiC(R′)=C(Et)1-BEt2X]. The cyclic salts KOtBu-4 and KOSiEt3-4 undergo a B1-substituent exchange to the acyclic cis-1,2-diborates K[Et3BC(Et)=C(Et)B(Et)OR] (K-10: R=tBu; K-11: R=OSiEt3).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260206
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    Synthesis and Structure of (Hydridosilyl)hydrazines (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 345-350 
    Details
    ISSN: 0009-2940
    Keywords: Silicon nitride ; (Hydridosilyl)hydrazines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of (hydridosilyl)hydrazines 1 - 12 has been prepared from the corresponding chloro-or bromosilanes and hydrazines in the presence of triethylamine as an auxiliary base. Methylsilyl (MeH2Si-), dimethylsilyl (Me2HSi-), and phenylsilyl (PhH2Si-) groups have been introduced as substituents. NMR spectra (1H, 13C, 15N, 29Si) have been measured and used to determine the rotation barrier about the N  -  N bond in (PhH2Si)(Me2HSi)N  -  N(SiHMe2) (9), which has been found to be 75 kJmol-1. The crystal structure of (PhH2Si)2N  -  N(SiH2Ph2 (7) features each of the two NNSi2 groups as nearly planar, but with a dihedral angle close to orthogonal. Such a structure is also implied for 9 on the basis of the NMR spectra.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260210
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    Dreizentren-oxidative Addition von Phosphor-Yliden an Ru3(CO)12 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 355-363 
    Details
    ISSN: 0009-2940
    Keywords: Ruthenium clusters ; Phosphorus ylides ; Oxidative addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three-Centre Oxidative Addition of Phosphorus Ylides to Ru3(CO)12Phosphorus ylides undergo oxidative addition to Ru3(CO)12 to yield a wide range of Ru3 clusters with triply bridging organic ligands derived from the ylides. Ph3P=CH2 forms HRu3(CO)9(μ31-Ph3P  -  CH  -  CO) (1) containing a phosphonio enolate. Ph3P=CH  -  CHO yields a product mixture containing the phosphonio enolate-bridged cluster and its PPh3 derivative 6, the phosphoniomethylidyne-bridged compound H2Ru3(CO)9(μ31-C  -  PPh3) (5), and the ketenylidene-bridged compound H2Ru3(CO)8(PPh3)(μ31-C  -  CO) (7). Thermal treatment converts the phosphonio enolate ligand (in 1) into the phosphoniomethylidyne ligand (in 5), and the latter into the ketenylidene ligand (in 7). With Ph3P=CH  -  C(O)Me and Ru3(CO)12 ortho1-metalated Ru3 derivatives 10, 11 of the phosphonio ketone R3P  -  C  -  C(O)Me are produced, and likewise with Ph3P=CH  -  COOEt the ortho1-metalated derivative 12 of the phosphonio ester R3P  -  C  -  CO2Et. Me3P=CH  -  COOtBu is oxidatively added to form HRu3(CO)9(μ31-Me3P  -  C  -  COOtBu) (13) bearing a phosphonio ester ligand.  -  The crystal structures of 6 and 13 are reported. The sequence of Ru3 clusters and the bonding modes of the μ3 ligands can be related to the surface reactions during Fischer-Tropsch catalysis.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260212
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    Contributions to the Chemistry of Boron, 214. Synthesis and Reaction Chemistry of Aminophosphanylboranes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 379-397 
    Details
    ISSN: 0009-2940
    Keywords: Boranes, amino-, phosphanyl- ; Diphosphadiboretanes ; Triphosphatriborinanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminochlorophosphanylboranes, (R2N)B(Cl)P(SiMe3)2 (1a  -  d) and (R2N)B(Cl)PH2 (2a  -  d), are obtained from elimination reactions between aminochloroboranes and LiP(SiMe3)2 and LiPH2, respectively. Selected reaction chemistry of (i1-Pr2N)B(Cl)P(SiMe3)2] (1a) with NH3, Me3SiN3, Cr(CO)5 · NMe3, and W(CO)5 · NMe3 is described. The azide (i1-Pr2N)B(N3)P(SiMe3)2 (12a) is stable at 25°C; however, thermolysis at 80°C provides a novel six-membered ring compound [(i1-Pr2N)BN(SiMe3)P(SiMe3)]2 (13a). The reaction of (Ph2N)B(Cl)P(SiMe3)2 (1b) with LiP(SiMe3)2 produces the only isolable bis(phosphanyl)borane (5b), while combination of (R2N)B(Cl)Ph2 with LiPH2 · DME yields new diphosphadiboretanes 6 {(R2N)BPH}2 (R2N=i1-Pr2N, Ph2N and tmp=2,2,6,6-tetramethylpiperidino) and triphosphatriborinanes 7 {(R2N)BPH}3 (R2N=(Me3Si)2N, Me2N and Et2N). Two salts, [(i1-Pr2N) DME]2 (8a) and [tmpLi · DME]2 (8c) (DME=ethylene glycol dimethyl ether) are also isolated. The results of molecular structure determinations for [(i1-Pr2N)Bn(SiMe3)P(SiMe3)]2 (13a), [tmpBPH]2 (4c), [tmpBPH]2 · Cr(CO)5 (7c), {[(Me3Si)2N]BPH}3 (4d), {[(Me3Si)2N]BPH}3 · Cr(CO)5 (7d), (Ph2N)B[P(SiMe3)2]2 (5b), and [(i1-Pr2N) · DME]2 (8a) are discussed.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260215
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    Reaktionen Pentafluorethyl-substituierter Bicyclo[2.1.1]hexan-Derivate (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 409-414 
    Details
    ISSN: 0009-2940
    Keywords: Carbocations, destabilized ; Solvolysis rates ; Wagner-Meerwein rearrangement ; Substitution, nucleophilic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Pentafluoroethyl-Substituted Bicyclo[2.1.1]hexane DerivativesThe effect of inductively electron-withdrawing substituents on the generation of 2-bicyclo[2.1.1]hexyl cations was probed by means of pentafluoroethyl groups. 2-Pentafluoroethyl-2-bicyclo[2.1.1]hexyl brosylate (4a) and triflate (4b) were found to rearrange with formation of the analogous 1-pentafluoroethyl-2-bicyclo[2.1.1]hexyl sulfonates 5a, b. Solvolytic displacement did not compete with the rearrangement but occurred on 5b at elevated temperatures. Deuterium labels revealed that the rearrangement proceeded stereospecifically, with the sulfonate departing and rebonding on the same side of the molecular plane. Complete inversion was observed during solvolysis of 5b in aqueous dioxane while some retention (16%) occurred in trifluoroacetic acid. Predominant inversion even with the analogous diazonium ion in water attests to the reluctant formation of 1-pentafluoroethyl-2-bicyclo[2.1.1]hexyl cations. Solvolysis rates of 4a, b and 5b were in close agreement with those of the analogous cyano derivatives, thus confirming that the resonance interaction of α1-cyano groups with carbocations is small.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260218
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    syn1-Periplanar Bisazo Skeletons  -  Syntheses and Reactions with Carbonylmetal Complexes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 429-440 
    Details
    ISSN: 0009-2940
    Keywords: syn1-Periplanar bisazo skeletons ; Carbonylmetal complexes ; Iron complexes ; Ruthenium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparatively useful synthesis for the novel, relatively mobile polycyclic syn1-periplanar bisazo polycycles 4 and 5 are based on hydrazine condensation with readily available dienedione 6 and acid-catalyzed rearrangement of bisurazole 12, respectively. In the preferred “closed” and “open” conformations of 4 and 5 the N=N bonds are 314 and 496 pm, respectively, apart (MMX). From the reactions of 4 and 5 with carbonyliron and -ruthenium compounds, complexes are derived which are typical of monoazo ligands [4 · Fe(CO)4 ≡ 20, 4 · Fe2(CO)7≡21, 4 · Fe3(CO)9≡22, 4≡[Fe2(CO)6]2≡23, 4 · Ru3(CO)9 · 24, 5 · [Fe2(CO)6]2 ≡ 25, 5 · Fe2(CO)6 · Fe3(CO)9 ≡ 26]. For 21, 23 and 26 crystal structure analyses were performed, confirming i.a. in 26 the unique presence of a Fe2(CO)6 and a Fe3(CO)9 fragment attached to two azo units of the same molecule.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260221
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    Fluorenylindate: Verbindungen mit schwachen In  -  C-Bindungen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 11-15 
    Details
    ISSN: 0009-2940
    Keywords: Indium compounds ; Indate, tetrafluorenyl ; Indate, chlorotrifluorenyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fluorenylindates: Compounds with Weak In  -  C BondsIn diethyl ether, fluorenyllithium reacts with indium(III) chloride to yield a lithium tetrafluorenylindate (1). Recrystallisation from THF gives [Li(THF)4][In(C13H9)4] (2). If the reaction is carried out in THF, the chlorotrifluorenylindate [Li(THF)4]-[ClIn(C13H9)3] (3) is isolated. According to crystal structure analyses 2 has long and weak In  -  C bonds [224.8(5) - 230.3(5) pm], while these distances in 3 are somewhat shorter [222.9 (5) - 226.7(4) pm].
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19931260103
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