SYNTHESIS AND CRYSTAL-STRUCTURE OF A NEW ACENTRIC OXYFLUORIDE - BA2TIOF6

Ba2TiOF6 is a new oxyfluoride obtained in single-crystal form by hydrothermal synthesis. The structure was solved by X-Ray diffraction data from a single crystal using 2688 independent reflections (R = 0.018 - Rw = 0.020). Ba2TiOF6 crystallizes in the monoclinic system (S.G.:Cc, acentric) with a = 11.446(2)Å, b = 9.304(2)Å, c = 7.252(1)Å, β = 126.67(2)°, and Z = 4. The structure is built up from TiO2F4 octahedra sharing opposite oxygen atoms to form infinite kinked chains running along the c axis. These chains [TiOF42n-n are separated from each other by barium and "independent" fluorine ions. The structure, described in term of two subnetworks of cationic tetrahedra FBa4, is compared with some silicate frameworks. © 1992 Academic Press, Inc.