Intercalation of the oxo-transfer molybdenum(VI) complex [MoO2{O2CC(S) Ph2}2]2– into a zinc(II)–aluminium(III) layered double hydroxide host. Catalysis of the air oxidalton of thiols

The intercalation of bis(2.2-diphenyl-2-sulfidoacetato)dioxomolybdate(VI)[MoO2{O2CC(S)Ph2}2]2–1 into an hydrotalcite-like zinc(II)-aluminium(III) layered double hydroxide by anion exchange yielded [Zn3–xAlx(OH)6]x+[{MoO2[O2CC(S)Ph2]2}y//2(NO3)x–y]x–·H2O (x= 0.75). Data from powder X-ray diffraction, IR and diffuse reflectance spectroscopy and thermogravimetnc analysis confirmed intercalation within a 13 A-height gallery, indicating that the molybdenum anion probably lies with its cis-dioxomolybdenum(VI) plane parallel to the hydroxide layers. Complex 1, immobilized in the layered double hydroxide, operates as an effective heterogeneous catalyst for the oxiDalton of thiols (PhSH) by either dioxygen or air as evaluated by gas chromatography. The active oxidant is [MoO2{O2CC(S)Ph2}2]2–, while a molybdenum(VI) species acts as the reductant by interaction with dioxygen to regenerate the molybdenum(VI) oxidant This constitutes the first reported heterogeneous catalyst containing an oxo-transfer MoVIO2complex capable of activating dioxygen. Oxidalion proceeds in ethanolic solutions without deactivation by water or excess thiol even at relatively high temperatures (up to 80°C). It is, therefore, concluded that intercalation of [MoO2{O2CC(S)Ph2}2]2– into the layered double hydroxide host inhibits the formation of a catalytically inactive molybdenum(V) species which was previously observed under homogeneous conditions.

[1]  T. Tatsumi,et al.  Shape Selective Epoxidation of Alkenes Catalyzed by Polyoxometalate-Intercalated Hydrotalcite. , 1992 .

[2]  Fabrizio Cavani,et al.  Hydrotalcite-type anionic clays: Preparation, properties and applications. , 1991 .

[3]  J. Ramírez,et al.  Molybdenum(VI)-dioxo complexes with sterically bulky thiocarboxylate ligands. Reactions with aliphatic thiols and electrochemical properties , 1991 .

[4]  B. Teo,et al.  Cluster of clusters. Structure of a new 25-metal-atom cluster [p-Tol3P)10Au13A1g12CL7](SbF6)2 containing a nearly staggered-eclipsed-staggered metal configuration and five doubly bridging ligands , 1991 .

[5]  P. Gómez‐Romero,et al.  Synthesis and structure of (Bu4N)[MoO(O2CC(S)Ph2)2]. The first mononuclear molybdenum(V) complex containing both coordinated thiolate and carboxylate groups , 1991 .

[6]  T. Pinnavaia,et al.  Catalytic autoxidation of 1-decanethiol by cobalt(II) phthalocyaninetetrasulfonate intercalated in a layered double hydroxide , 1991 .

[7]  T. Pinnavaia,et al.  New route to layered double hydroxides intercalated by organic anions: precursors to polyoxometalate-pillared derivatives , 1990 .

[8]  R. H. Holm.  The biologically relevant oxygen atom transfer chemistry of molybdenum: from synthetic analogue systems to enzymes , 1990 .

[9]  N. Ueyama,et al.  Catalytic air and amine N-oxide oxidation of p-substituted benzoin by molybdenum(VI) complexes. Identification of the deactivation process by dioxygen , 1990 .

[10]  P. Gómez‐Romero,et al.  Model compounds for the active sites of oxo-transfer molybdoenzymes. Synthesis, structural characterization, and electrochemical properties of [NH4]2[MoO2{O2CC(S)Ph2}2] , 1990 .

[11]  C. G. Young,et al.  Synthesis, characterization, and oxygen atom transfer reactions of {HB(Me2C3N2H)3}MoO{S2P(OR)2} and {HB(Me2C3N2H)3}MoO2{.eta.1-S2P(OEt)2} , 1988 .

[12]  T. Pinnavaia,et al.  Pillaring of layered double hydroxides (LDH's) by polyoxometalate anions , 1988 .

[13]  R. H. Holm,et al.  Kinetics, mechanisms, and catalysis of oxygen atom transfer reactions of S-oxide and pyridine N-oxide substrates with molybdenum(IV,VI) complexes: relevance to molybdoenzymes , 1988 .

[14]  Richard H. Holm,et al.  Metal-centered oxygen atom transfer reactions , 1987 .

[15]  R. H. Holm,et al.  Thiol as an electron donor in molybdenum oxo-transferase analog reaction systems: observations by fluorine-19 NMR spectroscopy and biological implications. , 1986, Journal of the American Chemical Society.

[16]  J. Berg,et al.  Model for the active site of oxo-transfer molybdoenzymes: synthesis, structure, and properties , 1985 .

[17]  J. Berg,et al.  Model for the active sites of oxo-transfer molybdoenzymes: reactivity, kinetics, and catalysis , 1985 .

[18]  N. Ueyama,et al.  Model reactions of molybdo-oxidase. Importance of water on the air oxidation of PPh3 by catalysis of [MoVIO2(Cys-OR)2](Cys-OR = S-deprotonated cysteine ester; R = Me, Et, Pri, or CH2Ph) in NN-dimethylformamide , 1984 .

[19]  Shigeo Miyata.  Physico-Chemical Properties of Synthetic Hydrotalcites in Relation to Composition , 1980 .

[20]  Shigeo Miyata.  The Syntheses of Hydrotalcite-Like Compounds and Their Structures and Physico-Chemical Properties—I: the Systems Mg2+-Al3+-NO3−, Mg2+-Al3+-Cl−, Mg2+-Al3+-ClO4−, Ni2+-Al3+-Cl− and Zn2+-Al3+-Cl− , 1975 .

[21]  W. Newton,et al.  Preparation and characterization of two series of dimeric molybdenum(V) N,N-dialkyldithiocarbamates. Their interrelation and chemistry as a model for the active site of nitrogenase , 1974 .

[22]  H. Taylor,et al.  Crystal structures of some double hydroxide minerals , 1973, Mineralogical Magazine.

[23]  K. Nakamoto.  Infrared spectra of inorganic and coordination compounds , 1970 .

[24]  Dudley H. Williams,et al.  Proton Positions in Brucite Crystals , 1956 .