Reactions of CH₃SH and CH₃SSCH₃ with Gas-Phase Hydrated Radical Anions (H₂O)_n^•–, CO₂^•–(H₂O)_n, and O₂^•–(H₂O)_n

Abstract

The chemistry of (H(2)O)(n)(•-), CO(2)(•-)(H(2)O)(n), and O(2)(•-)(H(2)O)(n) with small sulfur-containing molecules was studied in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry. With hydrated electrons and hydrated carbon dioxide radical anions, two reactions with relevance for biological radiation damage were observed, cleavage of the disulfide bond of CH(3)SSCH(3) and activation of the thiol group of CH(3)SH. No reactions were observed with CH(3)SCH(3). The hydrated superoxide radical anion, usually viewed as major source of oxidative stress, did not react with any of the compounds. Nanocalorimetry and quantum chemical calculations give a consistent picture of the reaction mechanism. The results indicate that the conversion of e(-) and CO(2)(•-) to O(2)(•-) deactivates highly reactive species and may actually reduce oxidative stress. For reactions of (H(2)O)(n)(•-) with CH(3)SH as well as CO(2)(•-)(H(2)O)(n) with CH(3)SSCH(3), the reaction products in the gas phase are different from those reported in the literature from pulse radiolysis studies. This observation is rationalized with the reduced cage effect in reactions of gas-phase clusters.

The reaction of CF2Cl2 with gas-phase hydrated electrons

“…49 Earlier studies in our group indicate that the actual collision rate of ionic water clusters lies between the two models. [50][51][52][53][54] The reaction efficiency can thus be determined using eqn (5).…”

Silicon‐Free SuFEx Reactions of Sulfonimidoyl Fluorides: Scope, Enantioselectivity, and Mechanism

“…Further mechanism investigations were made possible by utilizing the chirality of sulfur atom in the sulfonimidoyl fluoride 1 and its SuFEx products. Previous mechanism‐oriented reports have typically focused on substitution reactions on disulfides, yielding addition–elimination and S N 2 as the most widely accepted mechanisms, with the detailed mechanism being sensitive to the strain, counter cations, leaving groups, substituents on sulfur atom, nucleophiles, solvents,– and so on (see for an overview). Analogously, we considered as the three most likely mechanisms those summarized in Figure .…”

The interaction of negative charge with carbon dioxide – insight into solvation, speciation and reductive activation from cluster studies

“…Beyer and coworkers showed that collisions of hydrated CO À 2 cluster ions with CH 3 SH lead to the generation of formate anions, HCOO − [163,164]. The formation of C-C bonds in reactions of hydrated CO À 2 containing cluster ions has also been found [165][166][167].…”