Qualitative (sunlight) and quantitative (xenon light source) aspects of the photochemistry of [S2W18O62]4− in the presence of electron donors

The photoelectrochemical properties of the polyoxotungstate anion [S2W18O62]4− dissolved in acetonitrite have been surveyed. Qualitative studies revealed that the rate of oxidation of the electron donor in the presence of sunlight correlated well with the voltammetric peak potential for oxidation of the electron donor at a glassy carbon electrode. Quantitative studies on the photooxidation of tetrahydrofuran, dimethylformamide, triphenylphosphine and ferrocene, as detected at a platinum channel electrode in the presence of a xenon light source, were assigned to a CE mechanism. Simulated fits for the proposed mechanism provide estimates of the reaction rates and data are compared with those obtained previously on the basis of a CECE scheme for the molybdenum analogue.