Synthesis, crystal structure and properties of a novel copper(II) complex with tripod ligand tris(1H-benzimidazol- 2-ylmethyl)amine.

A five-coordinate copper complex with the tripod ligand tris(1H-benzimidazol-2-ylmethyl)amine (ntb), of composition [Cu(ntb)(H2O)] (C1O4)2 · C5H4N2O3 · H2O (C5H4N2O3 = 4-nitropyridine-N-oxide), was synthesized and characterized by means of elemental analyses, electrical conductivities, thermal analyses, IR, and U.V. The crystal structure of the copper complex has been determined by single-crystal X-ray diffraction, and shows that the CuII is bonded to a tris(1H-benzimidazol-2-ylmethyl)amine (ntb) ligand and a water molecule through four N atoms and one O atom, giving a distorted trigonal-bipyramidal coordination geometry with approximate C3 molecular symmetry. Cyclic voltammograms of the copper complex indicate a quasi-reversible Cu+2/Cu+ couple. Electron spin resonance data confirm a trigonal-bipyramidal structure and with g2 < gζ and a very small value of A2 (20 × 10-4 cm-1). [ABSTRACT FROM AUTHOR]