A SERIES OF MIXED-VALENT MOLYBDENUM MONOPHOSPHATES, ISOTYPIC WITH LEUCOPHOSPHITE REPRESENTED BY CSMO2P2O10 AND K1.5MO2P2O10.H2O

The structure of two mixed valent molybdenum phosphates, CsMo2P2O10 an d K1.5Mo2P2O10.H2O has been solved from single crystals by X-ray diffr action in the space group P2(1)/c with a = 9.428(1), b = 9.943(2), c = 12.348(2) angstrom and beta = 127.38(1)-degrees for CsMo2P2O10 and a = 9.721(2), b = 9.805(3), c = 12.329(3) angstrom and beta = 128.73(2)- degrees for K1.5Mo2P2O10.H2O. These compounds isotypic with NH4Mo2P2O1 0.H2O and RbMo2P2O10.(1 - x)H2O exhibit the leucophosphite structure. The possibility of cationic non stoichiometry in this structure is als o shown by the synthesis of two isotypic compounds A1.5Mo2P2O10.xH2O ( A = Rb, Tl). In these monophosphates, one site Mo(1) is fully occupied by Mo(V), whereas the other octahedral site Mo(2) exhibits a variable valency Mo(III)-Mo(IV) to Mo(V). The main difference between these di fferent phosphates deals with the distribution of the A cations inside the tunnels, depending upon their size and their content.