Reactions of the methylsulfinyl radical [CH₃(O)S˙] with oxygen (³O₂) in solid argon

Abstract

The atmospherically highly relevant methylsulfinyl radical (CH3(O)S˙) readily reacts with molecular triplet oxygen in cryogenic argon matrices containing small amounts of (3)O2. Comparison of experimental and computed IR- and UV/Vis spectra, including isotope exchange, show that the initially formed (3)O2 adduct has the structure of a peroxyl radical (CH3(O)SOO˙), which upon irradiation with UV light isomerizes to the methylsulfonoxyl radical (CH3SO3˙). The latter transforms into the methansulfonic acid radical (˙CH2SO3H) by irradiation with visible light. During the matrix photolysis small amounts of SO3 and the methyl radical were detected indicating competitive direct photodissociation.

The Trifluoromethyl Sulfinyl and Oxathiyl Radicals

“…[4] The smaller sulfinyl radicals CH 3 SOC [5] and HSOC [6] play important roles in the atmospheric oxidation of volatile sulfur compounds such as dimethyl sulfide( DMS) and H 2 S. Very recently, the spectroscopy, [7] photochemistry, [7b] oxidation, [8] and electronic structures [9] of CH 3 SOC have been studied in detail. [4] The smaller sulfinyl radicals CH 3 SOC [5] and HSOC [6] play important roles in the atmospheric oxidation of volatile sulfur compounds such as dimethyl sulfide( DMS) and H 2 S. Very recently, the spectroscopy, [7] photochemistry, [7b] oxidation, [8] and electronic structures [9] of CH 3 SOC have been studied in detail.…”

The Methylsulfonyloxyl Radical, CH3SO3

“…[8] Thef ormation of CH 3 SO 3 was reported by electron beam irradiation (3 MeV) of the CH 3 SO 3 À ion in ionic liquids at 77 K, [9] and very recently by the reaction of methylsulfinyl radicals (CH 3 SO) and molecular oxygen ( 3 O 2 )i ns olid argon. [10] Themolecular structures and the thermodynamic properties of CH 3 SO 3 and various isomers have been calculated at different theoretical levels. [11] According to these calculations, CH 3 SO 3 is highly unstable in the gas phase due to the low dissociation barrier for cleavage of the weak CÀSb ond (64.6 kJ mol À1 ,G 3XMP2//B3LYP/6-311 + G(3df,2p)).…”

Dihalogenated Methylperoxy Radicals: Spectroscopic Characterization and Photodecomposition by Release of HO.

“…[25] Oxidation of the counterpart FSOC (c) to FS(O)OOC (k, 1311.3, 1071.9,7 77.7/763.9, and 648.2/635.4 cm À1 ,T able S4) also occurs in the gas phase, resembling the oxidationo fC H 3 SOC to CH 3 S(O)OOC in Ar-matrix. [26] Thei dentification of FS(O)OOC is assured with the 18 O 2 -labeling experiments ( Figure S3), in which the band for the mostc haracteristic OÀOs tretching vibration at 1071.9 cm À1 shifts to 1013.1 cm À1 (Dv exptl = 58.8 cm À1 , Dv calcd = 58.2 cm À1 ). It is close to those in the two conformers of CH 3 S(O)OOC at 1100.3 and 1081.3cm À1 (Dv exptl = 61.0 and 58.0 cm À1 ).…”

“…Similar to the photochemistry of CH 3 S(O)OO . (→CH 3 SO 3 ⋅) and FSO 3 /O 2 (→FS(O) 3 OO . ), subsequent UV irradiation of FS(O)OO .…”