Trans hexaco-ordinate complexes of copper(II) and nickel(II) with 4(5)-hydroxymethyl-5(4)-methylimidazole - crystal structure and physico-chemical properties

摘要

Trans complexes of Cu(II) and Ni(II) with 4-hydroxymethyl-5-methylimidazole (L), of the general formula [ML4](NO3)(2) have been obtained. The complexes were characterized by single X-ray diffraction, elemental analysis, EPR spectroscopy, IR, FIR and Vis-NIR spectra. In these co-ordination compounds, the azole ligand has a dual nature. Two of these molecules are monodentate, co-ordinated through the '3' 'pyridynic' nitrogen atom of the imidazole ring, while the remaining two are bidentate ligands, the oxygen atom of the -CH2OH group being another electron donor (giving CuN4O2 and NiN4O2 chromophores). The structure of both chromophores is described by a slightly distorted tetragonal bipyramid. The stability constants and structures of the Cu(II) and Ni(II) complexes with the studied ligand (4-CH2OH-5-CH(3)im) in aqueous solution have been determined by potentiometric and spectrophotometric methods. The stability of the transition metal complexes of 4-CH2OH-5-CH(3)im depends on the presence of the hydroxymethyl group, the oxygen atom of which interacts with the metal-ion. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 18]