| Abstract
| - We report the first case of a metal complex that degrades a neurotoxin mimic under extremely mild conditions (pH 6.8, room temperature). The metallocene bis(η5-cyclopentadienyl)molybdenum(IV) dichloride (Cp2MoCl2; Cp = η5-C5H5) efficiently hydrolyzes the compound O,S-diethyl phenylphosphonothioate (DEPP), whose core functional group mimics the neurotoxin VX. Moreover, this is one of the few examples where phosphonothioate degradation yields exclusively the desired P−S bond scission under mild aqueous conditions (pH 7.2, 30 °C). Activation parameters for DEPP hydrolysis by Cp2MoCl2 in aqueous THF/acetone indicate (Ea = 86 kJ/mol, ΔH⧧= 83 kJ/mol, and ΔS⧧ = −10 J/(mol K)) an intramolecular hydrolytic process that goes through an ordered transition state. Alteration of the cyclopentadienyl ligand showed that ansa-Cp2MoCl2 with enhanced Mo(IV) electrophilicity significantly decreased DEPP hydrolysis, while (CpMe)2MoCl2 with increased Mo(IV) electron density had the opposite effect. These structure-activity relationships as well as the activation parameters indicate DEPP hydrolysis is achieved by nucleophilic attack of a Cp2Mo-bound hydroxide on the phosphonothioate.
- We report the first case of an organometallic complex that degrades a mimic of the chemical warfare agent VX under mild aqueous conditions. The metallocene bis(η5-cyclopenta-dienyl)molybdenum(IV) dichloride (Cp2MoCl2; Cp = η5-C5H5) efficiently hydrolyzes the compound O,S-diethyl phenylphosphonothioate (DEPP) with selective P−S bond cleavage.
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