title: A ladderlike chain aluminum fluoride ([Al2F8]2-)n with edge-sharing AlF6 octahedra.
abstract: A new aluminum fluoride, Al(2)F(8).2NC(5)H(6).C(6)H(3)(CO(2)H)(3), was synthesized under mild hydrothermal conditions (200 degrees C, 3 days) in the presence of 1,3,5-benzenetricarboxylic acid (btc) in pyridine/HF (pyr/HF) solvent. Its structure is characterized with single-crystal XRD analysis and high-resolution solid-state NMR. The inorganic framework consists of the corner- and edge-shared connections of AlF(6) octahedra. They are linked via a common edge and form a bioctahedral motif which is trans-connected through the corner-shared fluorine. It results in the formation of an original infinite double file of AlF(6) octahedra running along the a axis. A high-power decoupled MAS (27)Al{(19)F} Hahn echo NMR spectrum allowed us to distinguish the two crystallographic hexacoordinated Al sites. Four unresolved (19)F NMR signals are observed in the MAS spectra to account for the eight crystallographic fluorine atoms. Half of the terminal fluorine sites interact via strong hydrogen bonds with the ammonium groups of the pyridine moieties. The resulting mixed pyridine-fluoroaluminate chains are intercalated by the btc molecules which are hydrogen-bonded to the remaining free terminal fluoride anions through the protonated carboxylic acid function. The (1)H nuclei of both organic molecules are observed in the protonated form.
authors.affiliation: Institut Lavoisier (UMR CNRS 8637), Université de Versailles St Quentin en Yvelines, 45, Avenue des Etats Unis, 78035 Versailles, France. loiseau@chimie.uvsq.fr
authors.forename: Thierry
authors.initials: T
authors.lastname: Loiseau
authors.forename: Hervé
authors.initials: H
authors.lastname: Muguerra
authors.forename: Jerôme
authors.initials: J
authors.lastname: Marrot
authors.forename: Gérard
authors.initials: G
authors.lastname: Férey
authors.forename: Mohamed
authors.initials: M
authors.lastname: Haouas
authors.forename: Francis
authors.initials: F
authors.lastname: Taulelle