Synthesis, magnetic and electrochemical studies of binuclear copper(II) complexes derived from unsymmetrical polydentate ligands

Unsymmetrical binucleating polydentate ligands N,N-bis{2-hydroxy-5-methyl-3-(morpholin-1-lymethyl)benzyl -N',N'-diethyl-1,3-propane-diamine ((LH2)-H-1), N,N-bis{2-hydroxy-5-chloro-3-(morpholin-1-lymethyl)benzyl N',N'-diethyl-1,3-propane diamine ((LH2)-H-2) and N,N-bis{2-hydroxy-5-methyl-(3-piperidin-1-lymethyl)benzyl}cyclohexylamine ((LH2)-H-3) and their binuclear copper(II) complexes have been synthesized. These complexes were characterized by elemental analysis, IR, electronic and FAB mass spectra. Magnetic measurements were carried out in the temperature range 77-300 K. In these complexes the copper(II) ions show a moderate antiferromagnetic exchange interaction (-2J = 45-178 cm(-1)). Electrochemical studies of all the complexes show quasi-reversible two step single electron transfers at negative potentials. The first reduction peak was observed in the potential range -0.48 to -0.80 V and the second reduction peak was observed in the potential range -0.76 to - 1.40 V. The complexes of (LH2)-H-1 undergo reduction at a more negative potential than the complexes of the (LH2)-H-2 ligand. (C) 2005 Elsevier Ltd. All rights reserved.