title: Synthesis, X-ray and neutron diffraction characterization, and ionic conduction properties of a new oxothiomolybdate Li3[Mo8S8O8(OH)8[HWO5(H2O)]] x 18H2O.
abstract: The new oxothiomolybdate anion [Mo8S8O8(OH)8[HWO5(H2O)]]3- (denoted HMo8W3-) has been synthesized in aqueous solution by an acido-basic condensation reaction. Four (Mo(V)2S2O2) building blocks are connected through hydroxo bridges around a central [W(VI)O6] octahedron. X-ray and neutron diffraction studies have been performed on single crystals of the lithium salt Li3[Mo8S8O8(OH)8[HWO5(H2O)]] x 18H2O (Li3HMo8W x 18H2O) in an aqueous grown from HMo8W3- solution of LiCl (1 M). The neutron diffraction experiment enabled us to locate both the protons and the lithium ions. In the structure of Li3HMo8W x 18H20, ring-shaped anions interleaved by a cluster of disordered hydrogen-bonded water molecules stack on top of each other along lithium pillars. The lithium columns are formed by alternating edge-sharing octahedra and tetrahedra, with one lithium site in four being totally vacant. Ionic conductivity measurements on pressed pellets have shown that Li3HMo8W x 18H2O is a good ionic conductor at room temperature (sigma = 10(-5) S cm(-1)), but the ionic conductivity on single crystals is smaller by two orders of magnitude and is isotropic; this suggests the main path of conduction involves surface protons rather than lithium ions of the bulk.
authors.affiliation: Institut Lavoisier, IREM, UMR 8637, Université de Versailles Saint-Quentin, Versailles, France. dolbecq@chimie.uvsq.fr
authors.forename: Anne
authors.initials: A
authors.lastname: Dolbecq
authors.forename: Peloux Charlotte
authors.initials: PC
authors.lastname: du
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Auberty
authors.forename: Sax A
authors.initials: SA
authors.lastname: Mason
authors.forename: Philippe
authors.initials: P
authors.lastname: Barboux
authors.forename: Jérĵme
authors.initials: J
authors.lastname: Marrot
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Cadot
authors.forename: Francis
authors.initials: F
authors.lastname: Sécheresse