Journal of Physical Chemistry A, Vol.121, No.35, 6652-6659, 2017
A Coupled Cluster Investigation of SNO Radical Isomers and Their Reactions with Hydrogen Atom: Insight into Structures, Conformers, Barriers, and Energetics
High-level coupled cluster theory with single and double excitation, and including a perturbative triples correction (CCSD(T)) method and a series of Dunning's augmented correlation consistent basis sets, aug-cc-pVXZ (X = D, T, Q and 5) was applied to examine the conformational landscape of SNO radical system. The basis set has an important effect on the relative stability of SNO radical isomers; that is, at the CCSD(T)/aug-cc-pV5Z level of theory, the NSO radical is the most stable member of SNO radical family. This is in contrast to previous density functional theory prediction suggesting SNO radical is the most stable isomer. The CCSD(T)/aug-cc-pV5Z//CCSD(T)/aug-cc-pVTZ results suggest that the reaction between SNO radical isomers and hydrogen atom result in the formation of their [H,N,S,O] hydrides with HNSO hydrides being the most stable ones. Subsequently, these hydrides could decompose either into SH and NO radicals or into SN and OH radicals. The former pathway is preferred due to relatively lower barriers and favorable reaction energies. The results from our calculations support the role of S-nitrosothiols as NO shuttling agent in signaling-pathways and as a new source of HS and NO radicals in the lower atmosphere of Venus. Overall, these high-level calculations will play an important role in improving our understanding about the chemistry of S-nitrosothiols that has recently become a topic of interest because of their involvement in biochemical pathways and planetary processes.