CRYSTAL-STRUCTURE OF A NEW ACENTRIC OXIDE FLUORIDE OF V(IV) - BAVOF4

The structure of BaVOF4 has been determined by X-ray diffraction data from a single crystal obtained by hydrothermal synthesis: S.G. Fdd2 (a centric), Z - 16, a = 7.920(1), b = 27.608(2) and c = 7.375(1) angstro m with R = 0.0262 and R(w) = 0.0273 for 1508 independent reflections a nd 64 parameters. The network is built up from cis-linked VOF5 octahed ra forming infinite kinked chains running along the [101] and [101BAR] directions, connected by barium cations. The location of O2- and F- i ons is discussed using bond valence calculations. As for BaTiOF4 and s ome compounds in the series A(II)M(III)F5 (A = Ba, Sr and M = Ga, Al, Mn), the structure can be described in terms of a quasi hexagonal comp act planes stacking of Ba+2, O2- and F- ions.