Cyclic voltammetric and EPR spectral studies of copper(II)-chloro and -bromo complexes in organo and organo-aqueous media

Abstract

The electrochemical behaviour of copper(II)-chloro and -bromo complex species has been investigated in different organo (ethyl alcohol, DMSO, DMF and AN) and organo-aqueous media containing 0.1 M tetrabutyl ammonium perchlorate (TRAP) and 0.2 M KCl/KBr, respectively. The cyclic voltammetric parameters are calculated. Both the complex species involve two redox steps. The first couple (Cu 2 + / + ) involves a single electron, diffusion-controlled quasi-reversible electrode process, while the second step involves irreversible reduction of Cu I -halide species to metallic copper. Also, the reduction potential for the first couple (E p c l ) becomes more positive and that of the second step (E p c 2 ) becomes more negative with increasing percentage of a given organic solvent, indicating that the copper(I)-halo species becomes stabilized with respect to copper(II)-halo species. The EPR parameters (g∥, g⊥ and A∥) for the frozen solution spectra of CuCl 2 .2H 2 O and CuBr 2 .H 2 O in ethyl alcohol, DMSO, DMF and AN, each containing 0.1 M TBAP at liquid nitrogen temperature (77 K) are calculated and the results are discussed.