Synthesis and structural characterization of [Me4N](2)[W2O2(mu-S)(eta(2)-S-2)(4)]center dot MeCN, a novel oxo-thiotungstate(VI)

Orange red crystals of the new compound [Me4N](2) [W2O2 (mu-S-2)(eta(2)-S-2 )(4)] . MeCN were obtained from the reaction of a solution of [Me4N](2)[WOS 3] in MeCN with solid AuCN at room temperature. They are monoclinic, space group P2(1)/n, with a = 9.264(2), b = 17.736(3), c = 18.74215) Angstrom, be ta = 95.19(1)degrees; Z = 4. The crystal structure was determined from sing le crystal diffractometer data (MoK alpha-radiation) and refined to R = 0.0 50 (2955 reflections, 221 variable parameters). It is characterized by binu clear complex anions [[S-2)(2)OWSWO(S-2)(2)](2-) with close to C-2 symmetry Each metal center is surrounded by two end-on coordinating disulfide group s at distances ranging from 2.37 to 2.42 Angstrom which together with a bri dging sulfur atom (d(w-s) = 2.445 Angstrom) occupy the equatorial positions of a pentagonal bipyramid whose apices are defined by a terminal oxygen at om ((d) over bar(w-o) similar to 1.725 Angstrom) and one sulfur atom of the neighboring component at a distinctly larger distance ((d) over bar(w-s) s imilar to 2.82 Angstrom). Infrared spectra of the complex (KBr powder) showed v(W-O) and N(W-S) of br idging WS-W at 931 (vs) and 454 (m) cm(-1),respectively, V(W-S) of the WS2 unit appeared in the range between 465 and 438 cm(-1). The mass spectrum of the anion showed the molecular mass at m/z 688 for [W2O2S9](-) as well as peaks for other fragments.