Remarkable effect of hydroxylamine anion towards the solvolysis of sarin: A DFT study

The reaction of the nerve agent sarin with hydroperoxide (HOO-) and hydroxylamine anion (NH2O-) has been studied with a correlated molecular orbital and density functional theory. The profound effect was found for alpha-nucleophiles on the solvolysis process of sarin compared to alkaline hydrolysis. The enthalpy of activation calculated at MP2/6-31+G*/MPW1K/MIDII+Delta G(solv) (HF/6-31+G*) level of theory for the reaction of hydroxylamine anion with sarin is 5.2 kcal/mol lower than the barrier for alkaline hydrolysis. The charge descriptions of the alpha-nucleophiles seem to correlate well with their reactivity towards this organophosphorus compound. Conceptual DFT analysis also showed the similar trend for the solvolysis of sarin with these nucleophiles. The importance of intermolecular hydrogen bonding was also examined with the topological properties of electron density distributions for (-X-H center dot center dot center dot O, X = O, N) using Bader's theory of atoms in molecules (AIM) and natural bond orbital (NBO) methods. (C) 2010 Elsevier B.V. All rights reserved.