The synthesis and spectroscopic, magnetic and structural characterization of a complex of copper(II) with hexanoic acid, Cu-2(O2CC5H11)(4) are described. The same complex is formed by synthesis using either CuO or Cu2O. The compound exhibits a typical dinuclear paddle-wheel type structure, consisting of two copper(II) ions in square-pyramidal geometry bridged by four carboxylate anions in the xy plane. The IR spectrum shows that the Delta nu (coo) for this complex appears at 171 cm(-1) which corresponds to a bridging bidentade mode of coordination of carboxylate-lo-metal. Elemental analysis, EPR spectra and TG analysis were also performed. The magnetic susceptibility measurement confirms the antiferromagnetic nature of the copper-carboxylate coupling which is in agreement with the X-ray crystallography results. (C) 2000 Elsevier Science B.V. All rights reserved.