A Voltammetric Study on the One-Electron Redox Processes of the Dawson-Type Heteropolymolybdate Complexes

The electrochemical behaviors of the Dawson-type heteropolymolybdate anions, [S2Mo18O62]4−, [P2Mo18O62]6−, and [As2Mo18O62]6− were investigated at the glassy carbon (GC) electrode. In CH3CN where no protonation accompanies reduction, the voltammogram of the [S2Mo18O62]4− anion consists of four one-electron redox waves followed by an ill-defined wave while the [P2Mo18O62]6− and [As2Mo18O62]6− anions exhibit two one-electron redox waves; the one-electron waves are reversible and diffusion-controlled. The Dawson anions undergo successive two-electron reductions under the conditions where protonation can accompany reduction. The effect of the presence of acid on the voltammetric behaviors has also been discussed.