Please use this identifier to cite or link to this item:
|Title:||Structural, electronic and electron paramagnetic resonance study of (pyridine-2,6-dicarboxylato)copper(II) complexes with substituted imidazoles|
|Authors:||Ang, H.G. |
|Citation:||Ang, H.G., Kwik, W.L., Hanson, G.R., Crowther, J.A., McPartlin, M., Choi, N. (1991). Structural, electronic and electron paramagnetic resonance study of (pyridine-2,6-dicarboxylato)copper(II) complexes with substituted imidazoles. Journal of the Chemical Society, Dalton Transactions (12) : 3193-3201. ScholarBank@NUS Repository. https://doi.org/10.1039/DT9910003193|
|Abstract:||The molecular and electronic structures of a series of copper(II) complexes [Cu(pydca)L][pydca = pyridine-2,6-dicarboxylate; L = imidazole, 1-, 2- or 5-methylimidazole, 2-ethylimidazole or histamine (4-aminoethylimidazole)] have been studied. The structures where L is 1- (1-mim), 2- (2-mim) or 5-methylimidazole (5-mim) have been determined by single-crystal X-ray diffraction techniques: [Cu(pydca)(1-mim)(H2O)]·2H2O, triclinic, space group P1, a = 8.908(2), b = 15.729(3), c = 5.320(4) Å, α = 97.04(2), β = 91.83(2), γ = 101.64(2)°, Z = 2; [Cu(pydca)(2-mim)(H2O)]·H2O 2, monoclinic, space group P21/c, a = 12.105(3), b = 13.421(3), c = 8.277(3) Å, β = 96.9(0)°, Z = 4; [Cu(pydca)-(5-mim)(H2O)]·0.5MeOH 3, triclinic, space group P1, a = 7.575(2), b = 11.766(2), c = 16.203(3) Å, α = 69.39(3), β = 86.41(3), γ = 82.00(3)°, Z = 4, with two independent molecules in the unit cell. In each case the complex consists of discrete, monomeric units. The copper atom is co-ordinated to two carboxylate oxygen atoms [Cu-O(average) 2.0205(4), 2.0410(6) and 2.037(6) Å], to the pyridiyl nitrogen [Cu-N 1.895(4), 1.918(7) and 1.903(5) Å] and the imidazolyl nitrogen [Cu-N 1.925(4), 1.929(8) and 1.925(5) Å in 1-3]. The distorted square-pyramidal geometry is completed by a longer axial bond [Cu-O 2.390(4), 2.295(5) and 2.287(6) Å] to the oxygen atom of a water molecule. The effects of the 2-methyl substituent in 2 lead to a substantially longer Cu-N(pyridyl) bond. The solid-state EPR spectra of the complexes revealed strong dipole-dipole coupling except for that with L = imidazole where antiferromagnetic exchange was involved. The frozen-glass spectra had an unusual lineshape, atypical of tetragonally or tetrahedrally distorted mononuclear copper(II) complexes. The anisotropic EPR spectra of the five-co-ordinate copper(II) complexes were fitted by an orthorhombic spin Hamiltonian from which the g and 63Cu hyperfine matrices and linewidth parameters were determined by computer simulations. The methyl and ethyl derivatives of the [Cu(pydca)L(H2O)] complexes display similarities with superoxide dismutase with respect to the EPR characteristics, viz. the hyperfine and linewidth anisotropy.|
|Source Title:||Journal of the Chemical Society, Dalton Transactions|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Feb 13, 2019
WEB OF SCIENCETM
checked on Feb 13, 2019
checked on Jan 11, 2019
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.