V. Sanz

Polymer-supported molybdenyl thioglycolate as oxygen atom transfer reagent

Abstract Oxo-transfer reactions of a variety of substrates in DMF or methanol using polymer-supported molybdenyl thioglycolate (PSMT) have been investigated. The clean oxidation of Me 2 PhP, n -butanethiol or benzoin to yield Me 2 PhPO, disulfide or benzil, respectively, occurs in high yield. In the presence of air or pyridine N-oxide, a catalytic cycle is accomplished which goes on until the completion of the substrate.

Alkene epoxidations catalysed by Mo(VI) supported on Merrifield's polymer

High conversion and epoxide selectivity from alkenes is achieved with tert-butyl hydroperoxide and a polystyrene-grafted Mo(VI) catalyst, with no noticeable leaching of Mo from the support.

Synthesis and characterization of molybdenum(VI)-dioxo complexes containing both coordinated thiolate and carboxylate groups. Reactions with their own free ligands

The synthesis, characterization and spectroscopic properties of a group of Mo(VI) complexes having thiocarboxylate ligands of type [MoVIO2(O2CC(S)MePh-X)2]2 have been reported (X = H, p-Me, p-Cl). The peak potential for the Mo(VI) reduction increasing according to the electron-donor ability of X (Me > H > Cl). Reaction of these Mo(VI) complexes with their own free ligands has been studied by ESR and UV-Vis spectroscopy, yielding the monomeric [MoVO(O2CC(S)MePh-X)2]− as unique complex products. The kinetic study of this oxidation reaction has also been investigated.

Modeling for the active site nitrate reductase. Oxidation of the complex [MovO(O2CC(S) CH3Ph)2]− by nitrate and nitrite in methanol

Abstract Under acid conditions the [MoVIO2(O2CC(S)CH1Ph)2]2 reacts with thiols to yield the monomeric [MoVO(O2CC(S)CH3Ph)2] and disulfide. The reduced complex [MoVO(O2CC(S)CH3Ph)2]− can react with NO3− and NO2− in a one-electron step yeilding respectively NO2 and NO and the original molybdenum (VI)-dioxo complex. The experimental pseudo-first-order rate constant with respect to the Mo(V) complex at 25°C was found to be kobs=2.3×10−4s−1 for NO3− and kobs=1.0×10−2 for NO2−. Oxo transfers to and from the substrate have been coupled to produce a catalytic system which turns over the reaction RSH+(No3− or NO2−)+H+a 1 2 [ RS ] 2 +( NO ] 2 or NO )+ H 2 O , in which thiols, NO1− and NO2− serve as a model substrates and molybdenum complex as a catalyst. This result has permitted us to consider the system as a possible model for the nitrate reductase ‘Chlorella’ (S.P. Cramer et al., J. Am. Chem. Soc., 106 (1984) 1467; G.N. Geoige et al., Biochem. J., 259 (1989) 693).