Synthesis of a tetradentate piperazine ligand and a structural study of its coordination compounds

Abstract

A tetradentate ligand N, N′-bis(2-pyridylmethyl)piperazine (L1) and seven structures of its transition metal coordination compounds are described. Most of the compounds are of the general formula [M(L1)(NO 3) 2], with M=Cu 2+, Co 2+, Mn 2+and Cd 2+. In addition, a dimeric copper(II) compound, [Cu 2(L1)(Ac) 4](H 2O) 3, and polymeric silver(I) compounds, [Ag(L1)] n (NO 3) n (EtOH) n and [Ag(L1)] n (SO 3CF 3) n , were formed. The overall structure of L1 in the metal complexes A–G varies with the size and electronic properties of the metal ions. Mononuclear complex A is a five-coordinated, B is a six-coordinated, and C and D are eight-coordinated metal complexes. The dinuclear Cu complex, E, is four-coordinated, as are the polymeric Ag complexes, F and G. The polymeric Ag complexes contain meso-helical subunits and the anions are clathrated between the metal–ligand strands.