Hydrolysis of a VX-like Organophosphorus Compound through Dissociative Chemisorption on the MgO(001) Surface

Abstract

Organophosporous VX agent O-ethyl S-(2-diisopropylethylamino)ethyl methylphosphonothioate is one of the main nerve agents. For this reason, the search for ways to deactivate it is very important. In this work, hydrolysis and adsorption reactions of a VX-like compound (O,S-dimethyl methylphosphonothioate, DMPT) on the MgO(001) surface were studied by density-functional theory (DFT) using periodic boundary conditions. A degradation reaction mechanism was proposed and theoretically investigated on two types of MgO(001) surfaces: the terrace and the Al-doped. Conformations, free-energy differences, transition states, reaction barriers, and minimum-energy paths were computed. We found that the P–S bond, related to the agent toxicity, breaks via hydrolysis occurring spontaneously throughout the analyzed temperature range, 100–600 K. In the dissociative chemisorption of the DMPT molecule, the formation of the MgO:[PO(CH3)(OCH3)]+[SCH3]− intermediate is catalytically favored from a temperature of about 335 K for ...