Synthesis and ab Initio Structure Determination from X-Ray Powder Diffraction of MIL-12, a New Layered Fluoroaluminophosphate Templated with 1,3 Diaminopropane: [N2C3H12]Al2(PO4)(OHx, F5-x) (x~2)

MIL-12, formulated Al2(PO4)(OHx, F5-x)N2C3H12, with x~2, is a new layered fluoroaluminophosphate formed at the early stages of ULM-4 by hydrothermal synthesis using 1-3, Diaminopropane as a template (Al(OH)3/H3PO4/HF/1-3 DAP/H2O:ratio 1 : 1 : 3 : 0.5 : 80, 180°C/2 days). It crystallises in the monoclinic space group P21/m with a=11.072(1) ?, b=7.012 (2) ?, c=6.1096 (8) ?, beta=100.98 (1)° and Z=2. Its structure was solved ab initio from conventional X-ray powder diffraction data and refined by the Rietveld method with satisfactory crystal-structure model indicators (RB=0.088 and RF=0.062) and profile factors (Rwp=0.124 and Rp=0.161). It consists of [Al2(PO4)(OH, F)-25] macroanionic sheets perpendicular to the a axis in which OH- and F- ions are statistically distributed. Aluminum octahedra are linked together to form zig-zag chains running parallel to the b axis; the phosphate groups ensure the connection of the aluminum chains within the (100) layer. Protonated 1-3, Diaminopropane is interleaved between the sheets and ensures the cohesion of the structure by hydrogen bonds. Structural relations with other solids built with the same type of chains are presented.