Hydrothermal Synthesis and Structure of a Novel Molybdenum Phosphate: Na_4(H_3O) [Na(HPO_4)_2(PO_4)_4Mo_(18)O_(49)]·16H_2O

The title compound Na5H37P6Mo18O90 1 (Mr=1658) was synthesized under hydrothermal condition and its crystal structure was determined by X-ray diffraction. It crystallized in the monoclinic system, space group P21 with a =14.957(1), b =16.535(1), c = 16.159(1)?β=108.586(2)°, V=3787.85?, Dc =3.040g/cm3, Z=2,μ(MoK)=3.17mm-1, F(000)=3242. The final R and wR are 0.0500 and 0.1535 for 6643 observable reflections with I≥2?I), respectively. The result of structure analysis indicates that [Na(HPO4)2(PO4)4-Mo18 O49]5-anions 2 in 1 has the symmetry of C2V, in which each MoVIO6 octahedron is connected to adjacent PO4 tetrahedra through corner-sharing and to adjacent octahedra through edge-sharing or corner-sharing.