Hydrothermal synthesis and crystal structure of SrAl2(PO4)(2)F-2: a new three-dimensional framework with channels delimited by a helical anionic border

The new compound SrAl2(PO4)(2)F-2 has been synthesised by a hydrothermal me thod (700 degrees C, 195 MPa, 24 h). The structure was determinated by X-ra y diffraction on single crystal. SrAl2(PO4)(2)F-2 crystallises in the non-c entrosymmetric space group P2(1)2(1)2(1) (N degrees 19) with a = 12.026(1) Angstrom, b = 12.199(1) Angstrom, c = 4.666(1) Angstrom, V = 684.6(5) Angst rom(3) and Z = 4. Its structure is built up from corner-linkage between oct ahedral and tetrahedral units. The resulting tridimensional framework exhib its channels along [001] delimited by oxygen anions helically distributed. The Sr2+ cations are inserted inside the channels.