Voltammetric studies of polyoxometalate microparticles in contact with the reactive distillable ionic liquid DIMCARB

The voltammetry of the polyoxometalate salts [Bu4N](4)[SiW12O40] (alpha, beta, gamma* isomers), [Bu4N](4)[S2W18O62] (alpha, gamma* isomers) and [Bu4N](4)[S2Mo18O62] (alpha isomer) has been studied in the "distillable ionic liquid" DIMCARB (a mixture of adducts, both ionic and neutral, of dimethylamine and carbon dioxide). Dissolution of these salts tended to be slow and the anions, except [alpha-SiW12O4O40](4-), reacted with DIMCARB. However, high quality voltammograms were obtained from microparticles of the salts adhered to a glassy carbon electrode in contact with DIMCARB. Rapid dissolution of the reduced forms of each of the polyoxometalate anions provided reversible potential data. The higher basicity of the more highly reduced anions promoted interactions with the acidic solvent component of this medium. Comparison of reversible potentials indicated that the polarity of DIMCARB is similar to CH3CN, but smaller than that of conventional non-volatile ionic liquids and water. (c) 2005 Elsevier B.V. All rights reserved.