Copper(II) Complexes of Two New Pyridyl–Aliphatic Amine Ligands: Synthetic, Structural, EPR, and Magnetic Studies

Abstract

Two new polyamine ligands, L1 and L2, incorporating pyridyl and aliphatic amine donor sites have been prepared and their reaction with copper(ii) yields the mono- and binuclear complexes [Cu(L1)](ClO4)2 (1) and [Cl2Cu(L2)CuCl(H2O)]ClO4 (2), respectively. The X-ray structure of 1 confirms that the five nitrogen donors of L1 are bound to the central copper ion to give a distorted square pyramidal coordination sphere. In 2, L2 acts as a bridging ligand with its N3-donor coordination domains separated by a m-xylylene spacer group. An unusual feature of this latter complex is that symmetrical L2 gives rise to non-equivalent coordination behaviour at the individual copper sites; while both sites display five-coordination with distorted square pyramidal arrangements, they differ in having N3Cl2- and N3ClO-donor atom sets, respectively. The electron paramagnetic resonance (EPR) spectra of both complexes are discussed. Variable temperature magnetic susceptibility data confirmed the absence of magnetic interactions in 1 while a weak antiferromagnetic interaction between copper(ii) centres occurs in 2.