Synthesis, Crystal Structures and Characterization of Zinc(II) Complexes with the Tripod Ligand Tris( N -methylbenzimidazol-2-ylmethyl)amine and α, β-Unsaturated Carboxylates

Abstract

Three five-coordinate zinc complexes containing the tripod ligand, tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) and three different α,β-unsaturated carboxylates, with compositions [Zn(Mentb)(L1–3)](ClO4) · n H2O (L1 = trans-cinnamate; L2 = 2-hydroxycinnamate; L3 = 4-hydroxycinnamate; n = 0.5, 2, 1) were synthesized and characterized by means of elemental analyses, electrical conductivity measuerments, IR, UV, and 1H NMR spectra. The crystal structure of [Zn(Mentb)(L3)](ClO4) · DMF · C2H5OH · 0.5CH3OH has been determined by single-crystal X-ray diffraction, and shows that the Zn II atom is bonded to a tris( N -methylbenzimidazol-2-ylmethyl)amine (Mentb) ligand and a 4-hydroxycinnamate ligand through four N atoms and one O atom, resulting in a distorted trigonal-bipyramidal coordination geometry (τ = 0.86), with approximate C 3 symmetry.