Abstract
Two new zirconium (IV) fluorides, [H(2)dap]center dot(Zr2F10)center dot H2O (I) and [Hmeam](2)center dot(Zr2F10)center dot H2O (II), are synthesized and characterized by X-ray diffraction, thermal techniques and NMR spectroscopy. I is triclinic (P (1) over bar) with a = 6.805 (1) angstrom, b = 8.361(1) angstrom, and c = 11.853 (2) angstrom, alpha = 94.54(1)degrees, beta = 105.44(1)degrees, gamma = 108.75(1)degrees. II is monoclinic (C2/m) with a = 10.340(6) angstrom, b = 6.624(4) angstrom, c = 8.758(6) angstrom and beta = 110.57 (3)degrees The structure determinations, performed from single crystal X-ray diffraction data, lead to the R/R-w reliability factors 0.041/0.113 for I and 0.057/0.177 for II. The structures are built up from ZrF7 and ZrF8 units in I and only ZrF8 units in II. The polyhedra share common edges in order to form two different ZrF5 layers that are also found in [H2C2H10N2]center dot(Zr2F10)center dot H2O and (H3O)(2)center dot(Zr2F10)center dot H2O. On heating at 145 degrees C, [H(2)dap]center dot(Zr2F10)center dot H2O decomposes to give the anhydrous form [H(2)dap]center dot(Zr2F10) that undergoes two successive phase transformations at 220 degrees C and 290 degrees C. F-19 NMR spectroscopy confirms the structural features of [H(2)dap]center dot(Zr2F10)center dot H2O (I): two sets of three lines with a relative intensity 1:2:2 are attributed to five bridging fluorine atoms and to five nonbridging fluorine atoms. This spectroscopy demonstrates that a noticeable substitution of F- anions by hydroxyl OH- groups is excluded, together with the eventual substitution of H2O by HF molecules. (c) 2010 Elsevier Masson SAS. All rights reserved.