Synthesis of a new salt containing polyoxometallate anion and M?Cu?S cluster cation [MS4Cu4(γ-MePy)8][M6O19] (M = Mo,W). Crystal structure of [WS4Cu4(γ-MePy)8] [W6O19]

Reactions of (NH₄)₂MS₄, AgBr and CuBr in γ-methylpyridine produced one new compound, [MS₄Cu₄(γ-MePy)8][M₆O₁₉] (1, M = W; 2 , M = Mo), of which 1 was characterized by single crystal X-ray analysis. The crystal data: orthorhombic, Pbcn, a = 15.434(4), b = 16.732(2), c = 28.657(7) Å, V = 7400.8(8) ų, Z = 4 , R = 0.072 for 3121 independent data. The compound is the first example which contains both polyoxotungstate anion and heteropolynuclear cluster cation. In the structure of the cation four edges of the tetrahedral WS^2?₄ core are coordinated by four copper atoms, giving a WS₄Cu₄ aggregate of approximate D_2h symmetry. The differences between the reaction of Cu⁺ with MS^2?₄ and that of Ag+ with MS^2?₄ in pyridine and its derivatives are discussed.