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  • Chemistry  (57)
  • N ligands  (4)
  • Silicon  (2)
  • 11
    ISSN: 1434-1948
    Keywords: Rhodium ; Iridium ; N ligands ; Coordination modes ; Polymerizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of [RhI(cod)]+ and [IrI(cod)]+ by the new pyridine-amine-pyrrole ligands Py-CH2-N(R)-CH2-Pyr-H (HLR; R = H, Bzl, Bu) and the corresponding pyridine-amine-pyrrolate ligands [Py-CH2-N(R)-CH2-Pyr]- (LR-; R = H, Bzl, Bu, CH2Py) has been investigated. The neutral ligands HLR (R = H, Bu, Bzl) give [(HLR)MI(cod)]+ (M = Rh, Ir) in which HLR acts as a didentate ligand via the pyridine nitrogen (NPy) and the amine nitrogen (NRamine). The crystal structures of [(HLH)MI(cod)]PF6 (M = Rh: [1]PF6 and M = Ir: [2]PF6) have been determined. Deprotonation of [(HLR)MI(cod)]+ (M = Rh, Ir; R = H, Bzl, Bu) results in the neutral complexes [(LR)MI(cod)] (M = Rh, Ir) of the mono-anionic ligands LR- (R = H, Bzl, Bu). In square-planar [(LH)MI(cod)] (M = Rh: 3, M = Ir: 4), LH- is didentate via NHamine and the pyrrolate nitrogen (NPyr). The X-ray structures of 3 and 4 reveal that in both cases the uncoordinated NPy accepts a hydrogen bond from NHamine. The X-ray structures of [(LBzl)MI(cod)] (M = Rh: 5, M = Ir: 6), show that LBzl- is didentate via Namine and NPyr for M = Rh and tridentate for M = Ir. In solution LBzl- is tridentate for both M = Rh and M = Ir. The neutral complexes [{Py-CH2-N(R)-CH2-Pyr}MI(cod)] (M = Rh, Ir) cannot be oxidised selectively with H2O2. This is in marked contrast to the previously observed selective oxidation of the corresponding cationic complexes [{Py-CH2-N(R)-CH2-Py}RhI(cod)]+. Rhodium complex 5 is an active catalyst for the stereoregular polymerisation of phenylacetylene, whereas iridium complex 6 is inactive.
    Additional Material: 6 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 217-219 
    ISSN: 1434-1948
    Keywords: Nickel ; Iron ; Clusters ; Carbonyl complexes ; S ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Upon reaction of the mononuclear nickel dithiolate complex [Ni(dsdm)] (H2dsdm = N,N′-dimethyl-N,N′-bis(2-sulfanylethyl)ethylenediamine) with K[HFe(CO)4] in ethanol a unique reshuffling of ligands and of oxidation states takes place. This results in the formation of a novel tetranuclear complex [FeII(dsdm)Ni0(CO)3]2, in which a linear array of Ni-Fe-Fe-Ni is formed. The inner core of this complex consists of the dinuclear [Fe(dsdm)]2, and two Ni(CO)3 groups are bound at the periphery through one of the thiolate sulfurs.
    Additional Material: 1 Ill.
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  • 13
    ISSN: 1434-1948
    Keywords: Coordination chemistry ; α-Imino ketones ; CO complexes ; Iron complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of Fe2(CO)9 at room temperature in THF or toluene with the α-imino ketones R1N=C(R2)-C(R3)=O (L) (R1 = alkyl, R2 = H, Me, Ph, R3 = Me, Ph) (a-k), initially results in the formation of the mononuclear chelate Fe(CO)3(α-imino ketone) complexes 6 which can be isolated in moderate (6h) to high (6e-g) yield. Under these reaction conditions, complexes 6 subsequently react with [Fe(CO)4] fragments or dimerise, to form the dinuclear complexes Fe2(CO)6(α-imino ketone) (7a-j) or Fe2(CO)4(L-L) (8a,b,k), respectively. The complexes 8 contain two α-imino ketone ligands C-C coupled at the ketone carbon atoms. Complexes 8a,b react with CO at elevated temperatures to quantitatively yield Fe(CO)3(α-imino ketone) (6a,b). This reaction can be reversed photochemically. Irradiation of a solution of 6a,b in the low-energy band results in the reformation of 8a,b in almost quantitative yield. The extremely air-sensitive complexes 6 and the dinuclear complexes 7 and 8 have been characterised spectroscopically (IR, UV/Vis, 1H and 13C NMR) and by elemental analysis. The solid state structures of complexes 6g and 8a have been determined by single-crystal X-ray diffraction. The molecular structure of 6g confirms the flat σ-O,σ-N chelate coordination of the α-imino ketone. The structure of 8a consists of two metal-metal-bonded Fe(CO)2 units, bridged by a formally 10e-donating dianionic C-C coupled (tBu-ADO) ligand. A mechanism for the formation of complexes 8 is discussed.Supporting information for this article is available on the WWW under -//_/_http://www.wiley-vch.de/contents/jc_2005/2000/99351_s.pdf or from the author.
    Additional Material: 4 Ill.
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  • 14
    ISSN: 1434-1948
    Keywords: Pyridine ligands ; Bidentate bridging ligands ; Palladium ; Platinum ; N ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the new potentially tridentate ligand 3,5-bis(dimethylaminomethyl)pyridine (3) is described. Coordination chemistry of this ligand has been investigated with PdII and PtII precursor compounds. Both a bidentate bridging bonding motif and a monodentate bonding mode is observed. The latter compounds incorporate 3 by coordination through the pyridinic N atom only. The former complexes contain ligand 3 bonded to 2 metal centres by bridging through coordination of one trialkyl N donor atom and the pyridinic N atom. The solid-state structure of a ligand bridged Pd dimer has been elucidated by single-crystal X-ray diffraction and corroborates with the solid-state IR data that suggested a trans-PdCl2 unit was present.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1727-1733 
    ISSN: 1434-1948
    Keywords: Molybdenum ; Bisimidoaryl ; Alkoxide and phenoxide ligands ; Intramolecular coordination ; Imido complexes ; Chelates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterisation is reported of new, five-coordinate molybdenum(VI) bisimidoaryl complexes [Mo(NAr)2(O-N)(R)] [Ar = C6H3(iPr)2-2,6; O-N= 2-pyridyldiphenylmethoxide (a), 2-pyridyldimethylmethoxide (b), 8-quinolinolate (c); R = Cl, Me, CH2SiMe3] and the corresponding bisalkoxide (a, b) and bisphenolate [c, d = (OC6H4CH2NMe2-2)-] MoVI bisimidoaryl complexes [Mo(NAr)2(O-N)2]. These complexes can be formed by simple alcoholysis reactions between [Mo(NAr)2Cl2(DME)] and the appropriate alcohol in the presence of Et3N. The remaining chloride can be replaced by a methyl or trimethylsilylmethyl group by transmetallation with MeMgCl or LiCH2SiMe3. The solid state structure of [Mo(NAr)2(OCMe2-2-py)(CH2SiMe3)] (5) has been determined by single-crystal X-ray analysis. A similar synthetic procedure was used to synthesise and characterise [{Mo(NAr)2Me(OMe)}2] (7). The two methoxide ligands bridge between the two molybdenum(VI) nuclei. Compounds in which the ligand can form six-membered chelate rings {like [Mo(NAr)2(OC6H4CH2NMe2-2)2] (9) and analogues} are usually difficult to obtain in a pure form and yields are typically low.
    Additional Material: 3 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 505-507 
    ISSN: 1434-1948
    Keywords: Macrocycle ; Pyrazole ; N-Heterocycle ; Carbonate ; Copper ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 22-membered macrocycle, spanning four endocyclic pyrazole groups, viz. 1,4,9,14,17,22,27,28,29,30-decaaza-5,13,18,26-tetramethylpentacyclo[24.2.1.14,7.111,14.117,20]triacontane-5,7(28),11(29),12,18,20(30),24(27),25-octaene (22Pz), rendered the tetranuclear compound [Cu4(22Pz)2(CO3)2(MeOH)2](ClO4)4(MeOH)4. The copper(II) ions are in distorted octahedral N3O3 environments. All four pyrazole groups of each macrocycle participate in the coordination of the copper(II) ions. The cationic part of this compound is in fact a dimer of two macrocyclic ligands, each containing two copper(II) ions bridged by two carbonate ions in the highly unusual pentacoordinating fashion.Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2005/1999/98332_s.pdf or from the author.
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  • 17
    ISSN: 1434-1948
    Keywords: Copper ; Magnetic properties ; Supramolecular chemistry ; Three-dimensional architecture ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel three-dimensional copper(II) compound of the formula [Cu3(btre)5(H2O)2](ClO4)6·H2O (btre = 1,2-bis(1,2,4-triazol-4-yl)ethane) has been synthesized. The structure has been solved at 150 K by single-crystal X-ray analysis. The compound [C30H44Cu3N30O2·6(ClO4)·H2O] crystallizes in the triclinic space group P1bar with a = 12.488(1), b = 13.195(1), c = 19.756(2) Å, α = 78.959(8), β = 84.553(8), γ = 63.869(7)°, V = 2868.4(5) Å3, Z = 2 (trinuclear CuII units), 6484 reflections [I 〉 4σ(Ι)], RF = 0.0581, wR2 = 0.1214. The structure of this coordination polymer consists of a three-dimensional network built up from linear trinuclear CuII cations of formula [Cu3(btre)5(H2O)2]6+. This crystallographically independent unit comprises a linear array of three CuII ions linked by triple N1,N2-1,2,4-triazole bridges, yielding Cu1-Cu2 = 3.893(1) Å and Cu2-Cu3 = 3.889(1) Å. These linear trinuclear CuII units are linked by various pathways involving tridentate and tetradentate bridging btre ligands, which yields an unprecedented three-dimensional network. The CuII ions are weakly antiferromagnetically coupled with J = -1.01(2) cm-1 (based on the Hamiltonian: H = -J[SCu1·SCu2 + SCu2·SCu3] using the expression for the molar magnetic susceptibility S = 1/2 of a linear trinuclear system). The nature and the magnitude of the antiferromagnetic exchange have been discussed on the basis of the structural features.
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  • 18
    ISSN: 1434-1948
    Keywords: Crystal structures ; Nickel complexes ; Dinuclear complexes ; Magnetism ; Far-infrared ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand bis(2-benzimidazolyl)propane coordinates to NiII with chloride as an anion, thereby forming a dinuclear compound with the formula: [NiCl2(tbz)2]2(C2H6O)2. This compound crystallizes in the space group P21/c. Each five-coordinated NiII ion has a distorted trigonal bipyramidal environment which consist of two asymmetrically bridging Cl anions with distances of 2.3556(17) and 2.4275(16) Å, a terminal Cl anion with a distance of 2.3496(17) Å and two nitrogen atoms of the ligand with distances of 2.022(4) and 2.000(4) Å. The Ni-Ni distance is 3.5891(12) Å, while the Ni-Cl-Ni angle is 97.23(6)°. The magnetic properties of the compound, as studied in the range 5-280 K, have been fitted with a zero-field splitting parameter D (-14.3 cm-1) and a ferromagnetic exchange between the Ni ions in the dinuclear unit (J = +2.5 cm-1). The title compound appears to be the second example for a five-coordinated ferromagnetic dinuclear NiII compound of this type, and its magnetic properties appear to correlate with the ligand structure. With the availability of an increasing number of examples of such species it appears that antiferromagnetic exchange is found for all cases with the chromophore N2ClNiCl2NiClN2 where the MN2 ring is 5-membered. In the case, where this ring is six-membered, the exchange is ferromagnetic.
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  • 19
    ISSN: 1434-193X
    Keywords: Cavitands ; Crown compounds ; Calix[4]arenes ; Building blocks ; Modular approach ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crown[n]cavitands were synthesized by alkylation of tetrahydroxycavitands with polyethyleneglycol ditosylates. The bridging of two hydroxy groups at adjacent aromatic rings by a pentaethyleneglycol unit is favored over the bridging of two hydroxy groups at opposite aromatic rings. The presence of a sodium base enhances the formation of the 1,2-crown[n]cavitand and improves the yield. The combination of 1,2-crown[6]cavitands with calix[4]arenes or resorcin[4]arenes resulted in potential receptor molecules with large hydrophobic surfaces.
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  • 20
    ISSN: 1434-1948
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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