title: Synthesis and voltammetry of [bmim]4[alpha-S2W18O62] and related compounds: rapid precipitation and dissolution of reduced surface films.
abstract: 1-n-Butyl-3-methylimidazolium (bmim) salts of [alpha-SiM12O40]4- and [alpha-S2M18O62]4- (M = Mo, W) were synthesized and characterized. In sharp contrast to the multiple one-electron diffusion-controlled reduction processes expected in solution at a glassy carbon electrode, reduction of these salts beyond the one-electron level in CH3CN (0.1 M [bmim][PF6]) led to rapid precipitation of arrays of microdroplets or microcrystals onto the surface. Upon oxidation these arrays dissolved on the electrochemical time scale, resulting in voltammograms displaying both diffusion-controlled and surface-confined behavior. These novel observations appear to be related to the ability of the [bmim]+ cations and polyoxometalate anions to form ion clusters in solution and to the lower solubilities of the reduced salts.
authors.affiliation: School of Chemistry, The University of Melbourne, 3010 Victoria, Australia.
authors.forename: Andrew W A
authors.initials: AW
authors.lastname: Mariotti
authors.forename: Jingli
authors.initials: J
authors.lastname: Xie
authors.forename: Brendan F
authors.initials: BF
authors.lastname: Abrahams
authors.forename: Alan M
authors.initials: AM
authors.lastname: Bond
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Wedd
mesh_terms: D018360:Crystallography, X-Ray; D004566:Electrodes; D004573:Electrolytes; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D013997:Time Factors; D017973:Tungsten Compounds / Q000737:chemistry*
chemical_list: C519833:1-n-butyl-3-methylimidazolium alpha-S2W18O62; D004573:Electrolytes; D010087:Oxides; D012996:Solutions; D017973:Tungsten Compounds; D010100:Oxygen