Synthesis, crystal structure and properties of a copper(II) complex with the tripod ligand tris ( N -methylbenzimidazol-2-ylmethyl)amine and 4-hydroxycinnamate

Abstract

A five-coordinate copper complex with the tripod ligand tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) and 4-hydroxycinnamate, with the composition [Cu(Mentb)(4-hydroxycinnamate)](ClO4) · 0.5DMF, was synthesized and characterized by means of elemental analyses, electrical conductivities, thermal analyses, IR, and UV. The crystal structure of the copper complex has been determined by single-crystal X-ray diffraction, and shows that the CuII atom is bonded to a tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) ligand and a 4-hydroxycinnamate through four N atoms and one O atom, giving a distorted trigonal-bipyramidal coordination geometry (τ = 0.78), with approximate C3 molecular symmetry. Cyclic voltammograms of the copper complex indicate a quasireversible Cu+2/Cu+ couple. Electron spin resonance data confirm the trigonal–bipyramidal structure and indicate g ∥ < g ⊥ with a very small value of A ∥ (57 × 10−4 cm−1).