Syntheses and structural determination of new bis(9-tungstoarsenato)tris(dioxouranate(VI)) and its monooxovanadate(IV) derivative complexes

The [As2W18U3O74]12− complex is formed by the “self-assembly” reaction of View the MathML sourceWO42-,HAsO42- and View the MathML sourceUO22+ (uranyl nitrate) ions in acidic media. The anion complex is isolated as the potassium salt and characterized by elemental analysis, IR, UV–Vis, and X-ray single crystal analysis. The complex contains an anion in which three View the MathML sourceUO22+ ions are unsymmetrically sandwiched between two A-α-[AsW9O34]9− groups leading to a structure of C 3v symmetry. Each uranium atom adopts pentagonal-bipyramidal coordination, achieved by three equatorial bonds to one [AsW9O34]9−and two bonds to the other. The [As2W18U2V2O73]12−and also [As2W18U3O74]12− complexes are formed also, by reaction of the [KAs2W18U2O72]13− with VO2+ and View the MathML sourceUO22+ ions in 1:1 mole ratio. The cyclic voltammogram of [As2W18U2VO73]12− in acetate buffer (pH 4.7) shows a reversible one-electron redox process for VIV/V couple at +0.396 (Epc) and +0.432 V (Epa).