Structure of Hydrated Tungsten Peroxides [WO₂(O₂)H₂O]·nH₂O

Hydrated tungsten peroxides have been synthesized via the reaction of tungstic acid, H 2 WO 4, with aqueous solutions of hydrogen peroxide. Two crystalline phases with the formula [WO 2 (O 2 )H 2 O]· n H 2 O were obtained. X-ray powder diffraction data show that these two phases crystallize with monoclinic symmetry. Their structures were solved by using direct methods, and then full profile Rietveld refinements were carried out. As in other peroxo compounds, the coordination polyhedron around W VI can be described by a [WO 6 ] distorted octahedron in which one corner is replaced by a peroxo ligand (O 2 ). Both structures are made of zigzag double chains built up of edge-sharing octahedra along the b -axis. Coordinated water molecules join the chains to make the layers. In the case of n ≠ 0, additional water molecules link the layers together through hydrogen bonds.