Mechanism of Thiol-Induced Nitrogen(II) Oxide Donation by Furoxans: a Quantum-Chemical Study

Quantum-chemical calculations according to DFT with UB3LYP functional in the 6-311++G** basis set, and accounting for solvation effects by the polarized continuum method were used to study the mechanisms of thiol-induced fragmentation of unsubstituted and annulated furoxans with the elimination of nitrogen(II) oxide. A preference for NO formation according to the radical mechanism involving an attack by sulfanyl radical (HSE (TM)) on the carbon atom bonded to the N-oxide group was demonstrated for all systems. Anionic mechanisms involving HS- anions were not feasible in any of the cases due to high endothermic effects.