Binuclear copper(II) complexes of a new sulphur-containing binucleating ligand: structural and physicochemical properties

Abstract

The new ligand HL [2,6-bis{4-(benzimidazol-2-yl)-2-thiabutyl}-4-methylphenol] has been prepared. Its reaction with various copper(II) salts afforded a series of complexes 1–6 of general formula Cu₂L(X)Y₂(X = Y = Cl, 1; X = Y = Br, 2; X = OH, Y = CIO₄, 3; X = Y = NO₃, 4; X = N₃, Y = NO₃, 5; X = N₃, Y = CIO₄, 6). The molecular structure of 6 was determined by X-ray diffraction analysis. It exists as a discrete, dinuclear species in the solid state. The two copper sites are related by a symmetry axis and bridged by the phenoxo oxygen and a nitrogen from the µ-1,1-azide. Each copper is in a square-pyramidal environment, the base of which is constituted by an oxygen, a sulphur and a nitrogen from the organic ligand and the bridging azide nitrogen, while a perchlorato oxygen occupies the apical site. All compounds exhibit a high antiferromagnetic coupling which probably results from sulphur ligation. They exchange electrons at moderately positive potentials which reflects the balance between the hard phenoxo oxygen and the soft nitrogen and sulphur donors provided by the ligand.