Synthesis, structure, and properties of the cyclic mixed valence oxothiotungstate [W8S8O8(OH)8(H3WO6]2-

The novel polyoxothioanion [W8S8O8(OH)(8)(H3WO6](2-) was prepared by acidobasic condensation of four [W2S2O2](2+) thiofragments in the presence of tungstate ion. Rb-3[W8S8O8(OH)(8)(H3WO6] . 13H(2)O was isolated in the solid state and fully characterized by X-ray diffraction study (monoclinic, C2/m [a = 20.3540(1) Angstrom; b = 11.8042(2) Angstrom; c = 13.9355(2) Angstrom; alpha = 90degrees; beta = 131.134(1)degrees; gamma = 90degrees]. The molecular structure consists of an octameric {W8S8O8(OH)(8)} wheel encapsulating a central octahedron {H3WO6}(3-). The packing reveals a remarkable 3-D array resulting from connections between Rb+ and octameric wheels. The Rb+ cations form infinite parallel chains, which are mutually connected by the cyclic oxothioanions. The compound was also characterized by infrared spectroscopy and elemental analysis.