Effect of solvents on the electrochemical behaviour of copper(II,III) complexes with morpholinedithiocarbamato ligand

Department of Chemistry, University of Allahabad, Allahabad-211 002, Uttar Pradesh, India E-mail : dr_krishna_s@yahoo.co.in Manuscript received 5 September 2007, accepted 7 September 2007 The electrochemical behaviour of square planar [CuIII (morph-dtc)2]CIO4 (green), 1 and [CuII (morph-dtc)2] (brown), 2 (morphdtc- = morpholinedithiocarbamato anion) has been studied in dichloromethane (DCM), dimethylsulfoxide (DMSO), dimethylformamidc (DMF) and acetone containing 0.1 M TBAP as supporting electrolyte at a platinum disc working electrode using cyclic voltammetry. Two one-electron redox couples (Cu3+/2+) and (Cu2+/+) corresponding to [CuIII(morph-dtc)2]+ e-→ [CuII (morph-dtc)2] in the positive potential region and [CuII(morph-dtc)2]+ e-→ [CuI(morph-dtc)2]· in the negative potential region have been observed in DCM and DMSO media. In DMF and acetone, however, only a single quasircversible couple followed by an intense irreversible anodic peak, have been observed in the positive potential region. The present electrochemical studies reveal that the redox properties of complex 1 differ significantly in these solvents. It is observed that the case of reduction (Cu3+/2+) of this complex decreases in the order : acetone (E0' = 625 m V)→ DCM (E0'= 605 mV) → DMSO (E0' = 500 mV) → DMF (E0' = 380 mV)