Quantitative and Qualitative Photoelectrochemical Studies on the 18-Molybdodisulfate Anion [S2Mo18O62]4−

A. M. Bond, D. M. Way, A. G. Wedd, R. G. Compton, J. Booth, J. C. Eklund

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The heteropoly anion clusters [S2Mo18O62]4− and [S2Mo18O62]5− may be photochemically activated to generate extremely powerful oxidants. Quantitative photoelectrochemical measurements using laser excitation at 325 nm of acetonitrile solutions of [S2Mo18O62]4− containing the electron donors (ED), toluene and tetrahydrofuran, with hydrodynamic voltammetric monitoring at a platinum channel electrode are consistent with the following CECE mechanism: [S2Mo18O62]4− + ED (k1(hv)) → [S2Mo18O62]5− + ED+ (C); [S2Mo18O62]5− → [S2Mo18O62]4− + e (E); [S2Mo18O62]5− +ED (k2(hv)) ⇌ [S2Mo18O62]6− + ED+ (C); [S2Mo18O62]6− ⇌ [S2Mo18O62]4− + 2e (E); ED+ (fast) → products. Photochemical oxidation of other electron donors such as methanol, [BPh4], ferrocene, and Cr(CO)3 (arene) also occurs to generate [S2Mo18O62]5− and [S2Mo18O62]6− but not the more highly reduced [S2Mo18O62]7− and [S2Mo18O62]8− anions. It is concluded on the basis of these studies that [S2Mo18O62]4− is a potentially valuable photooxidant in the synthetic sense, since it may be readily synthesised in large quantities from inexpensive materials.

Original languageEnglish
Pages (from-to)3378-3384
Number of pages7
JournalInorganic Chemistry
Issue number13
Publication statusPublished - 1 Jun 1995

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