THE ORIGINAL STRUCTURE OF ZN3V4(PO4)(6) INVOLVING BIOCTAHEDRAL V2O10 UNITS AND ZNO5 TRIGONAL BIPYRAMIDS

A new monophosphate of trivalent vanadium and zinc Zn3V4(PO4)(6) was isolated and its structure has been determined from a single crystal X-ray diffraction study. It crystallizes in the space group P $$($) over bar 1 with a = 6.349(2) Angstrom, b = 7.869(1) Angstrom, c = 9.324(2) Angstrom, alpha = 105.32(1)degrees, beta = 108.66(2)degrees, and gamma = 101.23(2)degrees. This tridimensional framework consists of bioctahedral V2O10 units of two edge-sharing octahedra, monophosphate groups, distorted ZnO6 octahedra, and distorted ZnO5 trigonal bipyramids. In fact, the [V4P6O24](infinity) framework can be described as a stacking along b of [V4P4O24](infinity) layers parallel to the (a, c) plane, interconnected through layers of PO4 tetrahedra. The [V4P4O24](infinity) layers are themselves built up from two kinds of [V2P2O14](infinity) ribbons running along a; the latter are obtained by the assemblage of two [VPO8](infinity) single chains sharing the edges of their octahedra in two different ways. The ZnO5 bipyramids share two edges with two different V2O10 units, whereas the ZnO6 octahedra share their apices with the VO6 octahedra, the PO4 tetrahedra, and the ZnO5 bipyramids. A remarkable feature of this structure deals with the presence of numerous triply bonded oxygen atoms. (C) 1995 Academic Press, Inc.