Syntheses, Crystal Structures and Spectroscopic Studies of Bis1-methyl-3-(methoxycarbonylmethyl)-benzimidazolium(2+) CuBr4(2-) and ZnBr4(2-) Compounds

摘要

abstract_textpX-ray diffraction structure of two new bis 1-methyl-3-(methoxycarbonylmethyl) benzimidazolium(2+) CuBr4(2-) and ZnBr4(2-) compounds has been determined. Zn-crystal is monoclinic with perfect T-d symmetry of the ZnBr4 tetrahedron, whereas the Cu-compound is orthorhombic with D-2d symmetry of CuBr4 tetrahedron. The difference in these structures is described as due to the static Jahn-Teller effect. Vibrational spectroscopy (1800-3200cm(-1)) identified hydrogen bond network. NIR-UV-Vis spectra (5000-50000cm(-1)) are dominated by ligand-to-metal bands with d-d transition contribution. EPR results (Q-band) analyzed in terms of the MO-theory showed a very strong delocalization of unpaired electron density on ligands accompanied by the Cu(II) 4p(z) orbital contribution. This effect is partially compensated by charge transfer transitions to the EPR g-factor./p/abstract_text