Infrared absorption of CH3SO2 observed upon irradiation of a p-H2 matrix containing CH3I and SO2

Abstract

Irradiation with a mercury lamp at 254 nm of a p-H(2) matrix containing CH(3)I and SO(2) at 3.3 K, followed by annealing of the matrix, produced prominent features at 633.8, 917.5, 1071.1 (1072.2), 1272.5 (1273.0, 1273.6), and 1416.0 cm(-1), attributable to ν(11) (C-S stretching), ν(10) (CH(3) wagging), ν(8) (SO(2) symmetric stretching), ν(7) (SO(2) antisymmetric stretching), and ν(4) (CH(2) scissoring) modes of methylsulfonyl radical (CH(3)SO(2)), respectively; lines listed in parentheses are weaker lines likely associated with species in a different matrix environment. Further irradiation at 365 nm diminishes these features and produced SO(2) and CH(3). Additional features at 1150.1 and 1353.1 (1352.7) cm(-1) are tentatively assigned to the SO(2) symmetric and antisymmetric stretching modes of ISO(2). These assignments are based on comparison of observed vibrational wavenumbers and (18)O- and (34)S-isotopic shifts with those predicted with the B3P86 method. Our results agree with the previous report of transient IR absorption bands of gaseous CH(3)SO(2) at 1280 and 1076 cm(-1). These results demonstrate that the cage effect of solid p-H(2) is diminished so that CH(3) radicals, produced via UV photodissociation of CH(3)I in situ, might react with SO(2) to form CH(3)SO(2) during irradiation and upon annealing. Observation of CH(3)SO(2) but not CH(3)OSO is consistent with the theoretical predictions that only the former reactions proceed via a barrierless path.

Infrared absorption of trans-1-chloromethylallyl and trans-1-methylallyl radicals produced in photochemical reactions of trans-1,3-butadiene and Cℓ2 in solid para-hydrogen

“…For instance, the reaction C + CS 2 in p-H 2 produced C SCS, C CS, and C SC, 35 C + propene (C 3 H 6 or CH 2 =CHCH 3 ) produced the 2-chloropropyl radical (•CH 2 CHC CH 3 ), 36 and CH 3 + SO 2 produced CH 3 SO 2 . 34 In the reaction C + C 3 H 6 in solid p-H 2 , we observed IR lines ascribable to only the 2-chloropropyl radical, not the 1-chloropropyl radical, •CH(CH 2 C )CH 3 . This result is in contrast to the reported gaseous experiments in which formation of 1-chloropropyl is favored over 2-chloropropyl at least six fold.…”

“…As a consequence, photoproducts such as C atom and CH 3 radical produced on ultraviolet (UV) irradiation of C 2 (Ref. 31) and CH 3 I, [32][33][34] respectively, become excellent sources for studying bimolecular reactions in solid p-H 2 . We have employed this method to investigate the reactions of C or CH 3 with several small molecules in solid p-H 2 .…”

Infrared absorption of 3-propenonyl (⋅CH2CHCO) radical generated upon photolysis of acryloyl chloride [CH2CHC(O)Cl] in solid para-H2

“…[26][27][28][29][30] In this work, we have photolyzed a CH 2 CHC(O)Cl/p-H 2 matrix at 3.2 K with laser light at 193 nm and observed absorption lines ascribable to 11 fundamental vibrational modes of 3-propenonyl (·CH 2 CHCO) radical.…”

S-OO bond dissociation energies and enthalpies of formation of the thiomethyl peroxyl radicals CH3S(O)nOO (n=0,1,2)

“…Under atmospheric conditions equilibrium between CH 3 S and CH 3 SOO is rapidly established with approximately 20-80 % of CH 3 S in the form of CH 3 SOO at 298 K. The computational investigations of the equilibrium CH 3 S+O 2 CH 3 SOO [5][6][7][8][9] have produced a binding energy for S-OO ranging from 8.8 to 14.8 kcal mol -1 , depending on the method, in agreement with the experimental estimate of ~11 kcal mol -1 [4]. Photo-isomerization to the methylsulfonyl radical, CH 3 S(O) 2 , [10][11][12][13] and further coupling with O 2 give rise to the possible formation of a series of moderately bound peroxy radicals [14][15] (The notation by Yin et. al [16] is followed, where sulfonyl or sulfinyl oxygen atoms are put in parentheses).…”