Geometric and spectral characteristic of the tetrahalocuprate(II) complexes (HL)2CuX4 (X = Cl, Br). Crystal and molecular structures of bis(2-methylimidazolium) tetrabromocuprate(II)

The crystal and molecular structures of bis(2-methylimidazolium) tetrabromocuprate(II) are determined. The linear dependences of the degree of distortion of the CuBr 4 2- coordination polyhedron on the protonation constant of the organic cation are revealed for the structures with θ < 140°. The dependence of the hydrogen bond parameters (distances HBr and NBr, angle NHBr) on the degree of distortion of CuBr 4 2- is shown. The degree of distortion of CuX 4 2- (X = Cl, Br) is determined by the type of the organic cation and is almost the same for the CuBr 4 2- and CuCl 4 2- polyhedra. The empirical equations relating the degree of distortion of CuX 4 2- (X = Cl, Br) and the position of the Cu X ligand-to-metal charge-transfer band (νLMCT) are obtained. © 2009 Pleiades Publishing, Ltd.