Copper Complexes of the “Tripod” Ligand Tris(2-benzimidazolylmethyl)amine: Fiveand Six-Coordinate Copper(II) Derivatives and Some Copper(I) Derivatives

Abstract

A series of five-coordinate trigonal-bipyramidal and six-coordinate pseudooctahedral copper(II) complexes of the title ligand are reported. These systems are characterized by analytical data, IR, far-IR, ESR, and electronic spectra and magnetic susceptibility measurements. Although six-coordinate structures may pertain in some cases, in the solid state, all the compounds appear to have trigonal-bipyramidal structures in solution in methanol, where characteristic ESR spectra are observed, with g‖ < g﬩ and low values of |A‖|. Cyclic voltammetry and rotating platinum electrode dc polarography indicate the accessibility of stable copper(I) species in solution, which may have five-coordinate structures. Carbonyl adducts of these copper(I) complexes are formed in both MeCN (K = 10 atm-1) and DMF (K = 30 atm-1). Solid copper(I) complexes can be obtained under reducing conditions from the corresponding copper(II) compounds and also by reacting the ligand with copper(I) salts. © 1981, American Chemical Society. All rights reserved.