Determination of α-Keggin structure of [GeW11O39Ru(III)(H2O)]5-. Reaction of [GeW11O39Ru(III)(H2O)]5- with dimethyl sulfoxide to form [GeW11O39Ru(III)(dmso)]5- and their structural characterization.

Reaction of ruthenium((III))-substituted Keggin-type germanotungstate GeW(11)O(39)Ru(III)(H(2)O) (1) with a dimethyl sulfoxide (dmso) produced a dmso-coordinating derivative GeW(11)O(39)Ru(III)(dmso) (2). Structural characterization of compound 2 by using cyclic voltammetry, UV-Vis spectroscopy, IR spectroscopy, elemental analysis, (1)H-NMR spectroscopy and single crystal structure analysis (monoclinic, P2(1)/c, a = 13.461(1), b = 20.198(1), c = 18.078(1), β = 90.426(1), Z = 4) revealed that Ru(III) 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 Ru(III)-dmso was reversibly reduced to the Ru(II)-dmso derivative and oxidized to the Ru(IV)-dmso derivative. The redox potential in α-XW(11)O(39)Ru(III/II)(dmso) (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-GeW(11)O(39)Ru(II)(dmso).