ELECTROCHEMISTRY OF SODIUM TRANS-BIS(DIMETHYL SULPHOXIDE)TETRACHLORORUTHENATE(III) AND MER-TRICHLOROTRIS(DIMETHYL SULPHOXIDE)RUTHENIUM(III) - THE 1ST AND COMPLETE ELECTROCHEMICAL CHARACTERIZATION OF CHLORODIMETHYL SULFOXIDE RUTHENIUM(III) COMPLEXES

The results of an investigation of the electrochemical behaviour in dimethyl sulphoxide (DMSO) and aqueous solution of the two new halogen-DMSO complexes Na]trans-RuCl4(DMSO)2[ (I) and mer-RuCl3(DMSO)3 (II) are presented. Both complexes give trans-RuCl2(DMSO)4 upon bulk one-electron reduction of their DMSO solutions. In DMSO solution, complex II equilibrates with a less easily reducible isomer differing in the mode of binding of one DMSO ligand. This equilibrium, together with the homogeneous chemical reactions following the heterogeneous mono-electronic reduction of II, was estimated quantitatively by means of cyclic voltammetry. Cyclic voltammetry of I in aqueous medium shows the occurrence of an H2O/DMSO exchange reaction following its one-electron reduction at a Pt microelectrode. The complete scheme of the reactions which characterize the bulk electrolysis behaviour of the two complexes in aqueous medium is also reported.