Structures of Two New Polymorphic Forms of Hexavalent Tungsten Oxide Phosphates

Two new modifications of tungsten oxide phosphates, WOP2O7(o) and W2O3(PO4)2(o), were prepared, and their structures were determined by single crystal X-ray techniques. WOP2O7(o) crystallizes in the orthorhombic system, space groupPnma (No. 62) witha=16.662(2),b=5.147(2),c=6.612(4) ?. The structure was refined to anRfactor of 0.028 (Rw=0.022). The compound has a layered structure, where the layers are not bridged. Diphosphate group has a terminal oxygen atom bonded only with a phosphorus atom. W2O3(PO4)2(o) also crystallizes in the orthorhombic system, space groupPnma(No. 62) witha= 15.683(1),b=6.249(1),c=7.934(1) ?. The refinement yieldedR=0.019 (Rw=0.016). The structure is composed of dioctahedral W2O11groups and PO4groups to form a three-dimensional network.