Nitrosation of thiols and thioethers in the gas phase: a combined theoretical and experimental study.

Recent studies have demonstrated the biological importance of the interaction of nitric oxide with proteins such as cytochrome-c or hemoglobin. In particular, the possibility that the nitrosonium cation, NO(+), could reversibly bind to sulfide atom type was proposed. At pH values of biological relevance, nitrosation was proposed to occur through the action of NO(+) carriers such as nitrosothiols or nitrosamines. In this context, the gas phase chemistry of protonated nitrosothiols is studied in the present work by a combination of mass spectrometry and computational methods.

Gas-phase bimolecular reactions between (.)CH(2)-(CH(2))(n)-C(+)=O distonic ions and pyridine: a combined experimental and theoretical study.

The gas-phase reactivities of the well-known (.)CH(2)CH(2)C(+)=O and (.)CH(2)CH(2)CH(2)C(+)=O distonic ions towards neutral pyridine were studied both experimentally (six sector hybrid mass spectrometer) and theoretically (density functional theory and Møller-Plesset ab initio calculations). Competitively to the charge exchange and protonation processes, both radical cations react with pyridine by an initial bonding between the positive charge site of the ion and the lone electron pair of the neutral molecule. At variance with previously reported studies in which such a nucleophilic interaction was proposed to play only a transient catalytic role, the initial C-N bond is likely to remain in the observed ion-molecule reaction products. The structures of the ion-molecule reactions products were probed by collisional activation at high kinetic energy and the reaction pathways were tentatively proposed on the basis of labeling experiments and ab initio molecular orbital calculations.