Stabilization of the tungstyl ion configuration:the W(V) diphosphate KWOP2O7

A new W(V) diphosphate KWOP2O7 isotypic to the Mo(V) compound has been synthesized. It crystallizes in the space group P121/n1 with a = 5.0629(3), b = 11.770(2), c = 11.551(1), β = 91.039(6). This mixed framework of corner-sharing P2O7 groups and WO6 octahedra forms large tunnels where the K+ ions are located. This study evidences for the first time the ability of W(V) to form tungstyl ions in a phosphate matrix, the W(V) octahedra being characterized by an abnormally short W–O bond of 1.687 A, similarly to Mo(V).