title: Nitrosonium-catalyzed decomposition of s-nitrosothiols in solution: a theoretical and experimental study.
abstract: The decomposition of S-nitrosothiols (RSNO) in solution under oxidative conditions is significantly faster than can be accounted for by homolysis of the S-N bond. Here we propose a cationic chain mechanism in which nitrosation of nitrosothiol produces a nitrosated cation that, in turn, reacts with a second nitrosothiol to produce nitrosated disulfide and the NO dimer. The nitrosated disulfide acts as a source of nitrosonium for nitrosothiol nitrosation, completing the catalytic cycle. The mechanism accounts for several unexplained facets of nitrosothiol chemistry in solution, including the observation that the decomposition of an RSNO is accelerated by O(2), mixtures of O(2) and NO, and other oxidants, that decomposition is inhibited by thiols and other antioxidants, that decomposition is dependent on sulfur substitution, and that decomposition often shows nonintegral kinetic orders.
authors.affiliation: Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, CA 90095-1569, USA.
authors.forename: Yi-Lei
authors.initials: YL
authors.lastname: Zhao
authors.forename: Patrick R
authors.initials: PR
authors.lastname: McCarren
authors.forename: K N
authors.initials: KN
authors.lastname: Houk
authors.forename: Bo Yoon
authors.initials: BY
authors.lastname: Choi
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Toone
mesh_terms: D002384:Catalysis; D009569:Nitric Oxide / Q000737:chemistry*; D026403:S-Nitrosothiols / Q000737:chemistry*; D012996:Solutions
chemical_list: D026403:S-Nitrosothiols; D012996:Solutions; C504137:nitrosonium ion; D009569:Nitric Oxide