Preparation and X-ray crystal structure of [N(CH3)4]3[{H(SO4)W3O7(O2)2}2O]

The title peroxotungstosulphate as the first example of a polytungstosulphate has been prepared and its structure determined. The salt crystallizes under the conditions: [WO 4 2− ]=0.3−1.0 mol dm −3 , [WO 4 2− ]/[SO 4 2− ]=1−1/4, [WO 4 2− ]/[H 2 O 2 ]=1/2−1/4 and pH<1. The SO 4 2− tetrahedron shares its three vertices with two WO 5 (O 2 ) 2 decahedra and one WO 6 octahedron to form a diperoxotritungstosulphate moiety; the polyanion is made of the two moieties bridged with three μ-oxo groups