Infrared absorption of CH3OSO and CD3OSO radicals produced upon photolysis of CH3OS(O)Cl and CD3OS(O)Cl in p-H2 matrices

Abstract

Irradiation at 239 ± 20 nm of a p-H(2) matrix containing methoxysulfinyl chloride, CH(3)OS(O)Cl, at 3.2 K with filtered light from a medium-pressure mercury lamp produced infrared (IR) absorption lines at 3028.4 (attributable to ν(1), CH(2) antisymmetric stretching), 2999.5 (ν(2), CH(3) antisymmetric stretching), 2950.4 (ν(3), CH(3) symmetric stretching), 1465.2 (ν(4), CH(2) scissoring), 1452.0 (ν(5), CH(3) deformation), 1417.8 (ν(6), CH(3) umbrella), 1165.2 (ν(7), CH(3) wagging), 1152.1 (ν(8), S=O stretching mixed with CH(3) rocking), 1147.8 (ν(9), S=O stretching mixed with CH(3) wagging), 989.7 (ν(10), C-O stretching), and 714.5 cm(-1) (ν(11), S-O stretching) modes of syn-CH(3)OSO. When CD(3)OS(O)Cl in a p-H(2) matrix was used, lines at 2275.9 (ν(1)), 2251.9 (ν(2)), 2083.3 (ν(3)), 1070.3 (ν(4)), 1056.0 (ν(5)), 1085.5 (ν(6)), 1159.7 (ν(7)), 920.1 (ν(8)), 889.0 (ν(9)), 976.9 (ν(10)), and 688.9 (ν(11)) cm(-1) appeared and are assigned to syn-CD(3)OSO; the mode numbers correspond to those used for syn-CH(3)OSO. The assignments are based on the photolytic behavior and a comparison of observed vibrational wavenumbers, infrared intensities, and deuterium isotopic shifts with those predicted with the B3P86∕aug-cc-pVTZ method. Our results extend the previously reported four transient IR absorption bands of gaseous syn-CH(3)OSO near 2991, 2956, 1152, and 994 cm(-1) to 11 lines, including those associated with C-O, O-S, and S=O stretching modes. Vibrational wavenumbers of syn-CD(3)OSO are new. These results demonstrate the advantage of a diminished cage effect of solid p-H(2) such that the Cl atom, produced via UV photodissociation of CH(3)OS(O)Cl in situ, might escape from the original cage to yield isolated CH(3)OSO radicals.

Infrared spectra of free radicals and protonated species produced in para-hydrogen matrices

“…Similarly, ClCS was observed from photolysis at 248 nm of Cl 2 CS in solid p-H 2 . 34 Irradiation at 239 AE 20 nm of a p-H 2 matrix containing methoxysulfinyl chloride, CH 3 OS(O)Cl, and its perdeuterated isotopomer, CD 3 OS(O)Cl, yields absorption lines of all 11 vibrational modes of CH 3 OSO/CD 3 OSO in the spectral region of detection, 49 extending the information of only four bands observed in the photolysis of gaseous CH 3 OS(O)Cl with a stepscan Fourier-transform infrared (ss-FTIR) spectrometer. 50 As described in Section 1, CH 3 and C 2 H 5 are two free radicals that Momose and coworkers reported to be produced from photolysis in situ of CH 3 I and C 2 H 5 I, respectively.…”

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

“…The quantum solid para-hydrogen (p-H 2 ) has a diminished cage effect that allows the production of free radicals via photofragmentation [23][24][25] in situ or bimolecular reactions induced on irradiation. [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.…”

Methoxysulfinyl Radical CH3OSO: Gas-Phase Generation, Photochemistry, and Oxidation

“…19 The gas phase formation of CH 3 OSO from the neutralization of the corresponding cation was also confirmed by neutralization-reionization mass spectrometer (NRMS). 14 As for the IR spectroscopy characterization, five transient IR bands in the gas phase 13 and 11 IR fundamentals in para-H 2 matrix 18 have been observed for CH 3 OSO. Despite the progress made in the generation and characterization of CH 3 OSO, the knowledge about its reactivity including the photochemistry is limited.…”

“…The IR difference spectrum reflecting the change of the matrix-isolated CF 3 OSOCH 3 upon the laser irradiation is (5) 3153 ( 5) 3166 ( 2) 3149 (4) 3065 (18) 3066 ( 18) 3070 ( 1) 3063 ( 19) 1500 (11) 1499 (11) 1459 ( 6) 1501 ( 11) 1489 (12) 1489 (11) 1456 ( 22) 1490 ( 16) 1465 ( 2 shown in Figure 5A. The calculated IR spectra for the expected isomer CF 3 OSOCH 3 in the anti (Figure 5B) and syn conformations (Figure 5C) are depicted for comparison.…”

“…Experimentally, two methods for the generation of CH 3 OSO have been utilized (Scheme ). UV light photolysis of methoxysulfinyl chloride CH 3 OS­(O)Cl was most frequently used in producing CH 3 OSO radicals in solution, solid para -H 2 matrix, and gas phase for the subsequent characterization with electron paramagnetic resonance (EPR), matrix-isolation IR spectroscopy, time-resolved IR spectroscopy, and velocity map imaging apparatus . The gas phase formation of CH 3 OSO from the neutralization of the corresponding cation was also confirmed by neutralization-reionization mass spectrometer (NRMS) .…”