Synthesis, Structure, and Cooperative Proton−Electron Transfer Reaction of Bis(5,6-diethylpyrazinedithiolato)metal Complexes (M = Ni, Pd, Pt)

New proton and electron donors, MII(HL)2 (M = Ni, Pd, Pt; L = 5,6-diethylpyradzinedithiolate), as well as a proton and electron acceptor, PtIV(L)2, were prepared and characterized. The pH-dependent cyclic voltammetry of the MII(HL)2 complexes revealed a favorable Gibbs free energy (Kcom > 1) for the proton and electron transfer reactions from MII(HL)2 to MIV(L)2; i.e., the equilibrium for the following reaction lies to the right: MII(HL)2 + MIV(L)2 ⇄ 2MIII(HL)(L).