STRUCTURE OF TWO NEW POLYMORPHIC FORMS OF HEXAVALENT TUNGSTEN OXIDE PHOSPHATES

摘要

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 group Pnma (No. 62) with a=16.662(2), b=5.147(2), c=6.612(4) angstroms. The structure was refined to an R factor of 0.028 (Rw=0.022). The compound has a layered structure, where the layers are not bridged. Diphosphate group has a terminal O atom bonded only with a P atom. W2O3(PO4)2(o) also crystallizes in the orthorhombic system, space group Pnma (No. 62) with a=15.683(1), b=6.249(1), c=7.934(1) angstroms. The refinement yielded R=0.019 (Rw=0.016). The structure is composed of dioctahedral W2O11 groups and PO4 groups to form a 3-D network. 14 refs.