Voltammetric studies of the interaction of the lithium cation with reducedforms of the Dawson [S2Mo18O62}(4-) polyoxometalate anion

Multiple electron transfer steps observed in the reduction of [S2Mo18O62](4 -), when LiClO4 is used as electrolyte, are accounted for by assuming that Li+ acts as a moderately strong Lewis acid. For example, in the 95:5 CH3CN + H2O solvent mixture (0.1 M NBu4ClO4), the voltammetric behavior obtained on addition of Li+ can be simulated according a reaction scheme involving a n extensive series of reversible potentials and equilibrium constants. Prec ipitation of highly reduced polyoxometalate salts occurring at the electrod e surface complicates the voltammetry at very negative potentials when 0.1 M LiClO4 is used as the electrolyte. (C) 2000 Published by Elsevier Science B.V. All rights reserved.