Stabilization of a W(V) Diphosphate, W2O3·P2O7, with an Empty Tunnel Structure

A new form of WPO5 has been synthesized which is to our knowledge the second pentavalent tungsten phosphate actually known. This phase is isotypic to CsP8W8O40 and consequently can be described as a tungsten diphosphate, W2O3·P2O7, with large empty eight-sided tunnels. Although it fundamentally differs from the first form, which is a monophosphate, WOPO4, the two structures are closely related by the existence of ReO3type chains and slices, interconnected by P2O7 or PO4 groups, respectively. The stabilization of such an opened structure by adducts such as PbF2 or KBr is discussed