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The one-electron oxidation and reduction processes for some 80 dithiocarbamates of Cr, Mn, Fe, Co, Ni, and Cu reveal a marked dependence of redox potential on the metal 3dn electron configuration. For all the complexes examined, the relative ordering of the redox potentials with the dithiocarbamate substituents is remarkably consistent for both oxidation and reduction processes.

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An electrochemical study of the Mnn+ t R,dtc-system in aprotic solvents establishes that the dithiocarbamate ligand forms tris-chelated complexes of manganese in the three oxidation states 11, 111, and IV. Thuq, Mn(R,dtc), undergoes single oneelectron oxidation and reduction steps at a platinum electrode: [MnIV(R,dtc),]+ + e-t Mn111(R2dtc),; MnI"(R,dtc), t e-+ [MnIYR,dtc),]; These redox processes have been examined for 16 different substituents R by normal pulse voltammetry, ac voltammetry, cyclic voltammetry, coulometry, and exhaustive electrolysis. Several Mn(1V) complexes have been isolated and characterized. Tris-chelated Mn(I1) complexes have been characterized in solution. Titrations of %In2' into pyrrolidyldithiocarbamate solutions and vice verw have been monitored by electrochemical means. These experiments show the existence of 1:2 and 1:3 compounds ofMn(II), i.e., Mn(Pyrr(dtc)), and [Mn(Pyrr(dtc))J. A plot of E(red) vs. E(oxid) for the 16 substituents yields a linear relation with a slope of 1.1 over a potential range of approximately 300 mV confirming that the substituent effect of R imposes similar shifts on the oxidation and reduction potentials. The complex with benzyl substituents is hardest to oxidize and easiest to reduce: the dicyclohexyl-substituted complex is easiest to oxidize and hardest to reduce AIC308933