CONTRIBUTIONS TO THE REDOX-BEHAVIOR OF [M (IV)(S(2)C(2)R(2))(2)](0) TYPE DITHIOLENE COMPLEXES OF NI, PD, AND PT

Combined electrochemical and EPR spectroscopic investigations on [M(S( 2)C(2)R(2))(2)](0) dithiolene chelates containing the metal in the for mal oxidation state ''+4'' (M = Ni, Pd, Pt; R = CH3, C6H5, p-CH3C6H4 a nd p-CH3OC6H4) are reported. Spectroelectrochemically the ''M(III)'' s pecies are easily obtained under reductive conditions. The electrochem ical oxidation produces the ligand radical in all cases. Depending on the mode of the electrochemical potential (reduction/oxidation) the re dox reaction ''M(III)'' complex reversible arrow ligand radical can be switched. The chemical oxidation of the [M(IV)(S(2)C(2)R(2))(2)] comp lexes with Br-2 yielded paramagnetic. formally ''M(V)'' containing Ni and Pt species. EHT-MO calculations are used for the explanation of th e spin-density distribution in the [MS(4)] unit for the different oxid ation state of the metal.