Reactivity of one-, two-, three- and four-electron reduced forms of alpha-[P2W18O62](6-) generated by controlled potential electrolysis in water

Abstract

One, two, three and four electron reduced forms of α-[P2W18O62]6− in aqueous acidic electrolyte media have been selectively generated by bulk electrolysis from a solution that has an initial pH of 3.6. The reactivities of the reduced polyoxometalate anions and identities of products formed in the presence and absence of dioxygen have been assessed via oxygen and hydrogen Clark-type electrodes, a pH electrode and rotating disk electrode voltammetry. [P2W18O62]7− is stable to protons but is slowly oxidized by dioxygen (timescale: hours to days) back to [P2W18O62]6−. In contrast, [P2W18O62]8− reacts more rapidly with O2 and slowly with H+, whereas generation of the [P2W18O62]9− and [P2W18O62]10..