Quantum-chemical modeling of NO ligand activity in cationic nitrosyl iron complex [Fe(SC (NH2)2)2(NO)2]+ occurring in aerobic aqueous conditions

Abstract

The chemical reaction of a cationic ironnitrosyl complex with thiourea ligands of the composition [Fe(SC(NH2)2)2(NO)2]+ in aerobic aqueous conditions was studied via kinetic and quantum chemical modeling. An implicit expression is found for the kinetic curve which describes this process. The mechanism of interaction of the complex with molecular oxygen in the presence of water molecules was studied with density functional method. An optimized geometry of the initial, final, intermediate and transition states were obtained and the, energy profiles of the reactions were constructed. It was shown that the explicit inclusion of the water molecules in the reaction of the interaction of the complex with oxygen and the further transformation of the resulting products demonstrated not only the mechanism of the NO release, but also the intramolecular transformation of NO into NO2, NO2−, NO3−, ONOO−. A mechanism was proposed for the formation of a OH radical in the system and its release, along with the previously mentioned products, into solution.