Sulfide Oxidation by 2,6-Bis[hydroxyl(methyl)amino]-4-morpholino-1,3,5-triazinatodioxomolybdenum(VI): Mechanistic Implications with DFT Calculations for a New Class of Molybdenum(VI) Complex.

Sulfide oxidation is accomplished by a new class of dioxomolybdenum(VI) catalyst () that uses the tridentate 2,6-bis[hydroxyl(methyl)amino]-4-morpholino-1,3,5-triazine ligand to form a five-coordinate molybdenum(VI) center. Resonance Raman spectra show that the dioxo groups on the Mo(VI) oxygens readily exchange with water in an acetonitrile media that allows O labeling of catalyst . The model oxidation reaction was the conversion of thioanisole () to the corresponding sulfoxide with 4% of using an equimolar amount of HO in MeCN-.

Heterogeneous Organophosphate Ethanolysis: Degradation of Phosphonothioate Neurotoxin by a Supported Molybdenum Peroxo Polymer.

A polystyrene-supported molybdenum peroxo material [Mo-Y(s)] was applied toward the oxidative degradation of the organophosphate neurotoxin O,S-diethylphenyl phosphonothioate (1) through ethanolysis. In addition to the operational advantages of the heterogeneous reactivity, oxidative ethanolysis with a 10-fold excess of hydrogen peroxide yields only P-S bond scission to produce diethylphenyl phosphonate and ethyl sulfate. This is the first report of a molybdenum solid support that promotes the degradation of sulfur-containing organophosphate with the turnover benefits of heterogeneous catalysis.

Stereospecific cholinesterase inhibition by O,S-diethylphenylphosphonothioate.

The inhibition kinetics and stereospecificity of the chiral nerve agent derivative O,S-diethylphenylphosphonothioate (DEPP) were examined for two forms of acetylcholinesterase (human and eel) and equine butyrylcholinesterase. Both S- and R-DEPP are poor inhibitors of eel AChE (IC 150μM), consistent with a large, nondiscriminatory binding interaction in the active site of this enzyme. However, S-DEPP is active against human and equine AChE with low μM ICs.

Stereochemical inversion of phosphonothioate methanolysis by La(III) and Zn(II): mechanistic implications for the degradation of organophosphate neurotoxins.

The utility of phosphonothioate methanolysis to degrade organophosphate neurotoxins has prompted the stereochemical investigation of this useful transformation. The methanolysis of enantiomerically pure O,S-diethyl phenylphosphonothioate (5) was studied both in the presence and in the absence of metal ions known to catalyze the phosphonothioate → phosphonate transformation. This report outlines the syntheses of enantiomerically pure 5 and its methanolysis product O-ethyl O-methyl phenylphosphonate (7).

Accommodation of Ca(II) ions for catalytic activity by a group I ribozyme.

The wildtype Tetrahymena ribozyme cannot catalyze detectable levels of phosphotransfer activity in vitro on an exogenous RNA substrate oligonucleotide when calcium(II) is supplied as the only available divalent ion. Nevertheless, low-error mutants of this ribozyme have been acquired through directed evolution that do have activity in 10mM CaCl(2). The mechanisms for such Ca(II) accommodation are not known.

P-S Bond scission by bis(cyclopentadienyl)molybdenum(IV) dichloride, Cp(2)MoCl(2)(aq): first documented example of an organometallic complex hydrolyzing thiophosphinates.

Thiophosphinate hydrolysis involving P-S bond scission is desirable for the degradation of organophosphate neurotoxins, and we report the first case for such a hydrolytic process by an organometallic compound. The metallocene, bis(cyclopentadienyl)molybdenum(IV) dichloride, Cp(2)MoCl(2) (Cp = eta(5)-C(5)H(5)), hydrolyzes a variety of thioaryl diphenylphosphinates in an aqueous THF solution. P-S scission of p-methoxythiophenyl diphenylphosphinate has a 500-fold rate of acceleration in the presence of Cp(2)MoCl(2)(aq) with activation parameters of 20(3) kcal mol(-)(1) and -15(3) cal mol(-)(1) K(-)(1) for DeltaH(double dagger) and DeltaS(double dagger), respectively.