CS3MO4P4O22 - A MIXED-VALENT MONOPHOSPHATE ISOTYPIC WITH K2MO2P2O11

A new mixed valent molybdenum phosphate, Cs3Mo4P4O22 has been isolated. The structure determination of this phase from a single crystal shows its isotypy with the pure Mo(V) phosphate K2Mo2P2O11. It crystalizes in the space group P21/c with a = 10.134(1) Å, b = 10.104(1) Å, c = 9.952(1) Å, β = 100.44(1)°. The [Mo2P2O11]∞ framework consists of “Mo2P2O15” units built up from two octahedra and two tetrahedra, and delimits large intersecting tunnels where the Cs+ ions are located. The important difference with K2Mo2P2O11, deals with the stoichiometry of the interpolated Cs+ cations and their distribution in the structure: two sorts of sites are occupied by Cs+ instead of three by K+, owing to the larger size of cesium. Another characteristic of this phase concerns the mixed valency of molybdenum Mo(V)-Mo(VI), compared to the only presence of Mo(V) for K2Mo2P2O11. The electronic distribution in the two octahedral Mo sites is discussed. © 1994 Academic Press, Inc.