NH4[BAsO4F] - a new layer fluoro-boroarsenate with a silicate related topology

Mark Weller (1)

1 Chemistry

The fluoro-boroarsenate NH₄[BAsO₄F] has been obtained by the melt reaction of NH4H2AsO4, B(OH)3 and LiBF4. The dry reaction mixture, in a 3 : 3 : 2 ratio, was treated at 240 °C for 14 days. After cooling to room temperature and washing with hot water the product was isolated as colourless crystals and powder. The crystal structure was determined by single-crystal X-ray diffraction: monoclinic, space group Cc (no. 9), Z = 4, a = 4.4307(5) Å, b = 8.0991(9) Å, c = 12.674(2) Å, β= 90.230(6)°, V = 454.81(9) Å3, R1 = 0.0456, wR2 = 0.0900, Flack parameter = 0.13(3). The structure consists of [BAsO4F]− layers, separated by ammonium ions, having a unique orientations of the tetrahedra forming the constituent six-membered rings. The topology of the fluoro-boroarsenate layer is related to those of the silicate δ-Na2Si2O5 and the borophosphate Mg(H2O)2[B2P2O8(OH)2]•H2O. NH4[BAsO4F] was further characterised by powder X-ray diffraction, IR spectroscopy and EDX analyses.

Mots clés: Physical Sciences

Mark Weller. NH4[BAsO4F] - a new layer fluoro-boroarsenate with a silicate related topology. Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 635 (12), pp.1877. ⟨10.1002/zaac.200900183⟩. ⟨hal-00509659⟩