INTERCALATION OF THE OXO-TRANSFER MOLYBDENUM(VI) COMPLEX [MOO2(O2CC(S)PH(2))(2)](2-) INTO A ZINC(II)-ALUMINUM(III) LAYERED DOUBLE HYDROXIDE HOST - CATALYSIS OF THE AIR OXIDATION 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)Ph(2)}(2)]y/2(NO3)(x-y)](x-).H2O (x = 0.75). Data from powder X-ray diffraction, IR and diffuse reflectance spectroscopy and thermogravimetric analysis confirmed intercalation within a 13 Angstrom-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 oxidation of thiols (PhSH) by either dioxygen or air as evaluated by gas chromatography The active oxidant is [MoO2{O2CC(S)Ph(2)}(2)](2-) while a molyhdenum(IV) species acts as the reductant by interaction with dioxygen to regenerate the molybdenum(vr) oxidant. This constitutes the first reported heterogeneous catalyst containing an oxo-transfer (MoO2)-O-VI, complex capable of activating dioxygen. Oxidation proceeds in ethanoiic solutions without deactivation by water or excess thiol even at relatively high temperatures (up to 80-degrees C). It is, therefore, concluded that intercalation of [MoO2{O2CC(S)Ph(2)}(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.