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  • 1
    Electronic Resource
    Electronic Resource
    The crystal structure and IR spectra of μ-(bipyrimidine-N1,N1′,N5,N5′)-bis[(azido-N1)(methanol)(bipyrimidine-N1,N1′)copper(II)] bis(triflate) bis(methanol) (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 427-432 
    Details
    ISSN: 1572-8854
    Keywords: Dinuclear ; copper ; triflate ; bipyrimidine ; azido ; infrared
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of the title compound [Cu2(bipym)3(N3)2(CH3OH)2](CF3SO3)2(CH3OH)2 has been determined by X-ray diffraction. The crystals are triclinic, space group P1, with a = 8.1844(5), b = 11.0253(6), c = 12.9089(7) Å, α = 80.249(4), β, = 74.933(5), γ = 74.001(4)°, and Z = 1. The structure consists of a dinuclear Cu(II) unit formed of two didentate bipym ligands, one bis-didentate bipym ligand, two azido anions, and two coordinating methanol molecules. The Cu(II) atom is elongated tetragonally surrounded by two nitrogens of the didentate bipym ligand, one nitrogen of the bis-didentate ligand, and one nitrogen of the azido anion forming the equatorial plane with one nitrogen of the bis-didentate ligand and an oxygen atom of the methanol molecule as the axial atoms. A noncoordinating triflate anion and an additional methanol molecule are also in the crystal lattice and have a hydrogen bond distance of 2.801(3) Å with an angle of 157(4)°. The cations link by O – H ··· N bonds into infinite chains running in the c-direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021760420238
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis, Spectroscopy, and Magnetic Properties of Transition-Metal Complexes with the Diethyl 2-Quinolylmethylphosphonate (2-qmpe) Ligand - Crystal Structures of [Ni(2-qmpe)4(H2O)2](ClO4)2 and [Mn(2-qmpe)4(H2O)2](ClO4)2 Showing Unexpected O-Binding of the qmpe Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 169-175 
    Details
    ISSN: 1434-1948
    Keywords: Ligand field spectra ; Phosphonate complexes ; X-ray structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of transition-metal coordination compounds containing the ligand diethyl 2-quinolylmethylphosphonate (2-qmpe) is described. Complexes of CoII, MnII, NiII, CdII, and ZnII were found to be mutually isomorphous according to their X-ray powder diffraction patterns and IR spectra. The new coordination compounds were identified and characterized by elemental analysis, magnetic measurements, infrared and ligand-field spectra. The crystal structures of the complexes [M(2-qmpe)4(H2O)2](ClO4)2 (M = Ni, 1; Mn, 2) reveal six-coordinate [M(2-qmpe)4(H2O)2] cations with the qmpe ligand coordinating via the oxygen rather than via the nitrogen atom, as well as lattice perchlorate anions. The metal ion is octahedrally surrounded by the four oxygen atoms of the four organic ligands. The non-participation of the pyridine nitrogen atom is unusual. The two water molecules occupy the fifth and the sixth coordination sites in a trans configuration. The coordinated water molecules are strongly hydrogen-bonded to the pyridine nitrogen atom of the 2-qmpe, further stabilizing the solid-state structure. The geometry of the metal ion can be described as distorted octahedral. For the CuII complex, a hydroxo-bridged dinuclear structure of the type [Cu(2-qmpe)2(OH)(H2O)2]2(ClO4)2 is proposed, based on its spectroscopic and magnetic properties. Ligand-field spectra of the Co and Ni compounds were found to be in agreement with the tetragonally distorted octahedral geometry.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    A Unique Copper-Controlled Template Synthesis of Tetradentate N4-Donor Ligands and Their Propeller-Type Linear Trinuclear CuII Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 547-549 
    Details
    ISSN: 1434-1948
    Keywords: Copper ; Trinuclear ; Formamidines ; Magnetism ; Crystal structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In situ reaction of CuII triflate with aminopyridine or aminopyrimidine and triethylorthoformate in ethanol results in unique linear trinuclear CuII complexes with the general formula [Cu3(L-)4](CF3SO3)2(EtOH)x (L = dehydronated ligand N,N′-bis(pyridine-2-yl)formamidine or the new ligand N,N′-bis(pyrimidine-2-yl)formamidine). The structure [Cu-Cu-Cu angle 175.19(2)°] consists of four nearly flat molecules of the ligand which contribute to the propeller-type structure around the Cu-Cu-Cu axis. A strong antiferromagnetic interaction between the CuII ions is observed, resulting in an S = 1/2 ground state below 100 K.
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  • 4
    Electronic Resource
    Electronic Resource
    An Unprecedented, Copper-Mediated, In-Situ Multi-Step Ligand Formation - Synthesis, Structure, and Magnetism of Bis(μ-methoxo)bis[nitrato(2-methoxy- methylamino-3-methylpyridine)copper(II)] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1577-1579 
    Details
    ISSN: 1434-1948
    Keywords: Copper ; Methoxo-bridged complexes ; Crystal structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel chelating ligand, synthesized in situ within the coordination sphere of CuII from 2-amino-3-methylpyridine, MeOH, and dioxygen from the air, is found to form a strongly coupled, dinuclear methoxo-bridged CuII compound with the formula [Cu(L)(CH3O)(NO3)]2 (L = 2-methoxymethylamino-3-methylpyridine). The geometry around the copper atom is square pyramidal and the Cu-Cu distance within the dinuclear unit is 3.011(2) Å with an Cu-O-Cu angle of 103.13(8)°. Synthesis, X-ray crystal structure, and magnetism are reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis, X-ray Crystal Structure and Magnetism of [NiCl2{(bis(2-benzimidazolyl)propane}]2 · (C2H5OH)2 - A Second Example of a Ferromagnetically Coupled Five-Coordinated High-Spin Dichloro-Bridged Nickel(II) Dimer (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1337-1341 
    Details
    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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  • 6
    Electronic Resource
    Electronic Resource
    A Pulse Radiolysis Study of an Imidazolato-Bridged Asymmetric Dicopper(II) Complex: A Structural and Functional Mimic of Superoxide Dismutase (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1939-1943 
    Details
    ISSN: 1434-1948
    Keywords: Superoxide dismutase mimic ; Pulse radiolysis ; Imidazolato-bridged dicopper(II) complex ; Copper ; Radicals ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of a dicopper(II) complex with a pentadentate, imidazolato-bridged ligand having two different coordination environments to mimic the reactivity of superoxide dismutase has been investigated by pulse radiolysis. Pseudo first-order kinetics were observed for superoxide scavenging, with a very high rate constant of 1.9 ± 0.4 × 109M-1 s-1, consistent with catalytic dismutation of superoxide by the complex. This value is essentially constant over the pH range of 5 to 7, and agrees with earlier results obtained with the nitroblue tetrazolium assay.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Molecular mechanics modeling of organic backbone of metal-free and coordinated ligands (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 512-523 
    Details
    ISSN: 0192-8651
    Keywords: molecular mechanics ; force field ; transition metal compounds ; coordinated ligands ; organic backbone ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new molecular mechanics force field has been developed that takes into account the fact that, upon coordination to a transition metal ion, the redistribution of electron density leads to small but significant structural changes in the organic backbone of the ligand. Structural studies indicate that the perturbation by coordination to a metal ion extends to the α-carbon atom of the donor, the perturbation is roughly independent of the metal center for M2+ and M3+ and negligible for M+, and the perturbation of the Cα(SINGLE BOND)Cα′ bond is roughly independent of the donor atom. New parameter sets for oxalates, imidazoles, and pyrazoles are also presented. The refined parameters have been validated with a large number of monodentate, multidentate, and macrocyclic ligands.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 512-523, 1998
    Additional Material: 2 Ill.
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  • 8
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    Dimerization of a His117Gly Azurin Mutant by External Addition of 1,ω-Di(imidazol-1-yl)alkanes (1998)
    American Chemical Society
    Details
    Publication Date: 1998-04-30
    Print ISSN: 0006-2960
    Electronic ISSN: 1520-4995
    Topics: Biology , Chemistry and Pharmacology
    Published by American Chemical Society
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