Proton induced reduction of WO42- under sulfide-polysulfide environment: A new route to the synthesis of complexes containing {(W2S2)-S-V(mu-S)(2)}(2+), {W2O2(mu-S)(2)}(2+) and {W2O2(mu-S)}(6+) cores

Acidification of an alkaline solution containing tungstate, polysulfide and tetraethylammonium chloride afforded the products (Et(4)N)(2)[W2S2(mu-S)(2)(S-4)(2)] (1), (Et(4)N)(2)[W2O2(mu-S)(S-2)(4)] (2) and (Et(4)N)(2)[W2O2(mu-S)(2)(S-4)(2)] (3) depending on the pH of the solution. This method is a new rational and general method of the syntheses of binuclear sulfur bridged oxo- or sulfide-compounds of tungsten Oil or (VI). The X-ray crystal structure of 1 has been determined. The structure consists of disordered tetra-ethylammonium cations and binuclear units of the complex anion [W2S12](2-) with the metal atoms displaying distorted square pyramidal geometry. The structural features of all the complexes are supported or revealed by the IR, electronic and FAB mass spectroscopic data. Cyclic voltammetric study of (I) shows two irreversible single step metal centred reduction waves in the potential range -1.0 to -1.8 V.