HYDROTHERMAL SYNTHESIS AND CRYSTAL-STRUCTURE OF [NI(H2O)4][VO(PO4)]2, A NICKEL(II) VANADYL(IV) PHOSPHATE

The new M2+/V4+/P/O phase [Ni(H2O)4][VO(PO4)]2 was prepared by hydrothermal synthesis and characterized by X-ray crystallography and thermogravimetric analysis. Crystal data: tetragonal space group I 4/mmm, a = 6.251(1)Å, c = 13.338(3)Å, V = 521.2(3)Å3, Z = 2, Dcalc = 2.845 g/cm3; structure solution and refinement based on 176 reflections with I0 ≥ 3σ(I0) (MoKα radiation, λ = 0.71073Å) converged at R = 0.0564. The structure consists of {VO(PO4)} layers, constructed from VO5 square pyramids and PO4 tetrahedra, linked by NiO6 octahedra. The structure is distinct from that of Ni0.5[VO(PO4)] · 1.5H2O, which exhibits a three-dimensional network structure with tunnels accommodating the aquo ligands. © 1993 Academic Press, Inc.