A new zirconium-containing polyoxotungstate [{W 5 O 18 Zr(µ-OH)} 2 ] 6-2 was prepared by alkalinization of a solution of the monomeric form [W 5 O 18 Zr(H 2 O)] 2-1. The crystal structure of ( n Bu 4 N) 6 [{W 5 O 18 Zr(µ-OH)} 2 ]‚ 2H 2 O (monoclinic; space group C2/c; a ) 26.086, b ) 17.018, c ) 32.891 Å; β ) 112.23°) reveals that two Lindqvist-type units {ZrW 5 O 18 } 2-(shortly ZrW 5 ) are linked through two hydroxo bridges (Zr-OH-Zr) with Zr in sevenfold coordination. Both compounds 1 and 2 were characterized by IR and Raman spectroscopy. EXAFS analysis of 1 at the W L III -edge agrees with the hypothesis of a monosubstituted Lindqvist structure. The 183 W NMR spectrum of 2 in acetonitrile is consistent with the solid-state structure assuming a dynamic process implying likely the µ-hydroxo bridge. A brief discussion is given on the relevance of molecular zirconium-containing polyoxotungstates to heterogeneous catalysis since these compounds can be envisioned as molecular analogues of zirconia-supported tungsten catalysts.

The synthesis and characterization of a series of mixed W-Zr polynuclear Lindqvist-type complexes, deriving from hexatungstate [W6O19]2-, are described in this work. This family of compounds is built from {W5O18Zr}2- moieties as shown by the X-ray structures of the monomeric [W5O18Zr(H2O)(3-n)(DMSO)n]2- (n = 1 and 2) and dimeric [{W5O18Zr(mu-OH)}2]6- anions. A comprehensive spectroscopic study (183W NMR, FTIR, Raman, EXAFS, and EPR) of these compounds is presented. The goal of incorporating Zr(IV) cations into an oxotungstic core is to obtain spectroscopic models that could mimic the interactions that develop in supported catalysts between the active phase and the supporting oxide. This work tends to show that these molecular compounds can be regarded as soluble structural analogues of WOx/ZrO2 catalysts, which are interesting candidates for the skeletal isomerization of light n-alkanes.

. EX-AFS spectroscopy as a tool to probe metal-support interaction and surface molecular structures in oxide-supported catalysts: application to Al2O3-supported Ni(ii) complexes and ZrO2-supported tungstates. Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2009, 11, pp.7527

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Tungsten I 5700 Synthesis and Characterization of Zr(IV) Polyoxotungstates as Molecular Analogues of Zirconia-Supported TungstenCatalysts. -The new compound (IV) crystallizes in the monoclinic space group C2/c with Z = 4. The anionic unit of this compound consists of two Lindqvist-type {ZrW5O18} 2units which are linked by two µ-OH bridges with Zr in sevenfold coordination. Both compounds (III) and (IV) are characterized by IR and Raman spectroscopy. EXAFS analysis of (III) at the W L III -edge agrees with the hypothesis of a monosubstituted Lindqvist structure. The 183 W NMR spectrum of (IV) in MeCN is consistent with the solid-state structure assuming a dynamic process implying likely the µ-OH bridge. A brief discussion is given on the relevance of molecular zirconium-containing polyoxotungstates in heterogeneous catalysis because these compounds can be seen as molecular analogues of zirconia-supported tungsten catalysts. -(VILLANNEAU*, R.; CARABINEIRO, H.; CARRIER, X.; THOUVENOT, R.; HERSON, P.; LEMOS, F.; RIBEIRO, F. R.; CHE, M.; J. Phys. Chem. B 108 (2004) 33, 12465-12471; Lab. Chim. Inorg. Materiaux Mol., CNRS, Univ. P. et M. Curie, F-75252 Paris, Fr.; Eng.) -Schramke 43-026

Structure D 2000Zirconium-Substituted Isopolytungstates: Structural Models for Zicronia-Supported Tungsten Catalysts. -The synthesis and characterization of a series of mixed W-Zr polynuclear Lindqvist-type complexes containing [W5O18] 2units are described and single crystal XRD results are given for (II) (monoclinic, space group P21/c, Z = 4) and (III) (monoclinic, P21/n, Z = 4). A comprehensive spectroscopic study ( 183 W NMR, FT-IR, Raman, EXAFS, and EPR) of (I), (II), (III), and (Bu 4 N) 6 [W 5 O 18 Zr(OH)] 2 ·2H 2 O [preparation see CI-2004-43-026] indicates that these molecular compounds can be regarded as soluble structural analogues of WOx/ZrO2 catalysts, which are interesting candidates for the skeletal isomerization of light n-alkanes. -(CARABINEIRO, H.; VILLANNEAU*, R.; CARRIER, X.; HERSON, P.; LEMOS, F.; RAMOA RIBEIRO, F.; PROUST, A.; CHE, M.; Inorg. Chem. 45 (2006) 5, 1915-1923; Lab. Chim. Inorg. Materiaux Mol., CNRS, Univ. P. et M. Curie, F-75252 Paris, Fr.; Eng.) -Schramke 22-008

Inorganic chemistry Z 0100 EXAFS Spectroscopy as a Tool to Probe Metal-Support Interaction and Surface Molecular Structures in Oxide-Supported Catalysts: Application to Al 2 O 3 -Supported Ni(II) Complexes and ZrO2-Supported Tungstates-[73 refs.]. -(CARRIER*, X.; MARCEAU, E.; CARABINEIRO, H.; RODRIGUEZ-GONZALEZ, V.; CHE, M.; Phys. Chem. Chem. Phys. 11 (2009) 35, 7527-7539; Lab. React. Surf., Univ. P. et M. Curie, F-75252 Paris, Fr.; Eng.) -Schramke 46-221