HYDROTHERMAL SYNTHESIS OF NA2(MOOPO4)2(HPO4).2H2O - A LAYERED MOLYBDENUM(V) PHOSPHATE STRUCTURE AND ITS RELATIONSHIP TO 2VOSO4.H2SO4

The hydrothermal synthesis and structure of the molybdenum (V) phosphate, Na2(MoOPO4)2(HPO4) · 2H2O, was determined and compared to the closely related 2VOSO4 · H2SO4 (B. Jordan and C. Calvo, Can. J. Chem. 51, 2621 (1973)). Na2(MoOPO4)2(HPO4) · 2H2O crystallizes with lattice parameters a = 6.452(2)Å, c = 15.999(1)Å, and z = 2 in the tetragonal space group I4 mmm and was refined to Rf = 0.041 and Rwf = 0.044 with 426 reflections for which I > 2σ. The structure is made up of layers of MoOPO4 composed of alternating molybdenum oxygen octahedra and phosphate tetrahedra. The layers are linked by disordered phosphorus tetrahedra forming tunnels. Thermogravimetric analysis, infrared, solid state, NMR, and ESR spectra indicate the presence of water in the tunnels and molybdenum with an oxidation state of (V). © 1991.