Determination of α-Keggin structure of [GeW11O39RuIII(H2O)]5−. Reaction of [GeW11O39RuIII(H2O)]5− with dimethyl sulfoxide to form [GeW11O39RuIII(dmso)]5− and their structural characterization
Reaction of ruthenium(III)-substituted Keggin-type germanotungstate [GeW11O39RuIII(H2O)]5− (1) with a dimethyl sulfoxide (dmso) produced a dmso-coordinating derivative [GeW11O39RuIII(dmso)]5− (2). Structural characterization of compound 2 by using cyclic voltammetry, UV-Vis spectroscopy, IR spectroscopy, elemental analysis, 1H-NMR spectroscopy and single crystal structure analysis (monoclinic, P21/c, a = 13.461(1), b = 20.198(1), c = 18.078(1), β = 90.426(1), Z = 4) revealed that RuIII was incorporated in the α-Keggin-type framework and coordinated by dmso through an Ru–S bond. The IR spectra of 1 and 2 were very similar, indicating that 1 also has an α-Keggin structure. Cyclic voltammetry indicated that the incorporated RuIII-dmso was reversibly reduced to the RuII-dmso derivative and oxidized to the RuIV-dmso derivative. The redox potential in [α-XW11O39RuIII/II(dmso)]n− (X = P, Ge, Si) decreased in the order of P > Ge > Si. Reaction of the complex 2 with ascorbic acid produced a one-electron-reduced compound [α-GeW11O39RuII(dmso)]6−.