Paraoxon and parathion hydrolysis by aqueous molybdenocene dichloride (Cp2MoCl2): First reported pesticide hydrolysis by an organometallic complex

We report the first case of an organometallic complex that effectively hydr olyzes the organophosphate pesticides parathion and paraoxon. The complex i s the water-soluble compound bis(eta(5)-cyclopentadienyl)molybdenum(IV) dic hloride (1), which hydrolyzes parathion to produce ethanol and deethyl para thion in a biphasic reaction in D2O. Rate accelerations were 130 and 10(5) at pH 7 and 3, respectively. Paraoxon is readily hydrolyzed by 1 to yield p -nitrophenol and diethyl phosphate with rate accelerations of 2300 and 27 a t pH 7 and 3, respectively. Kinetic data for paraoxon hydrolysis by 1 are c onsistent with a process that involves intermolecular (Delta S-double dagge r = -49 +/- 10 eu) hydroxide attack on the phosphate triester in which the aquated 1 serves as a coordinated Lewis acid that activates' the organophos phate. Interestingly parathion hydrolysis by 1 occurs via nucleophilic atta ck at the alpha-carbon of the phosphorothioate pesticide that involves C-O bond cleavage. These parathion results represent one of the few cases of th is type of unusual hydrolytic chemistry and the first case of an organometa llic complex that accelerates organophosphate pesticide hydrolysis.