Ba-2(VO2)(PO4)(HPO4)center dot H2O, a new barium vanadium(V) phosphate hydrate containing trigonal bipyramidal VO5 groups

摘要

The hydrothermal synthesis, single crystal structure, and some physical properties of Ba-2(VO2)(PO4)(HPO4) . H2O, a new barium vanadium(V) phosphate hydrate, are reported. This phase is built up from one-dimensional chains of unusual VO5 trigonal bipyramids and (H)PO4 tetrahedra, fused together via V-O-P linkages. These anionic chains propagate along the polar [010] direction. 11-Coordinate barium cations and water molecules occupy the interchain regions and link the chains together. Structural data for this phase and other known barium vanadium phosphates are briefly compared. Crystal data: Ba-2(VO2) (PO4)(HPO4) . H2O, M-r = 566.57, monoclinic, space group P2(1) (No. 4), a = 5.0772(5) Angstrom, b = 8.724(2) Angstrom, c = 10.806(1) Angstrom, beta = 90.795(8)degrees V = 478.6(1) Angstrom(3), Z = 2, R = 2.65%, R-w = 2.89% [147 parameters, 1893 observed reflections with I > 3 sigma(I)]. (C) 1998 Academic Press. [References: 29]