Infrared absorption of CH3OSO and CD3OSO radicals produced upon photolysis of CH3OS(O)Cl and CD3OS(O)Cl in p-H-2 matrices

Abstract

Irradiation at 239 +/- 20 nm of a p-H-2 matrix containing methoxysulfinyl chloride, CH3OS(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 nu(1), CH2 antisymmetric stretching), 2999.5 (nu(2), CH3 antisymmetric stretching), 2950.4 (nu(3), CH3 symmetric stretching), 1465.2 (nu(4), CH2 scissoring), 1452.0 (nu(5), CH3 deformation), 1417.8 (nu(6), CH3 umbrella), 1165.2 (nu(7), CH3 wagging), 1152.1 (nu(8), S=O stretching mixed with CH3 rocking), 1147.8 (nu(9), S=O stretching mixed with CH3 wagging), 989.7 (nu(10), C-O stretching), and 714.5 cm(-1) (nu(11), S=O stretching) modes of syn-CH3OSO. When CD3OS(O)Cl in a p-H-2 matrix was used, lines at 2275.9 (nu(1)), 2251.9 (nu(2)), 2083.3 (nu(3)), 1070.3 (nu(4)), 1056.0 (nu(5)), 1085.5 (nu(6)), 1159.7 (nu(7)), 920.1 (nu(8)), 889.0 (nu(9)), 976.9 (nu(10)), and 688.9 (nu(11)) cm(-1) appeared and are assigned to syn-CD3OSO; the mode numbers correspond to those used for syn-CH3OSO. 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-CH3OSO 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-CD3OSO 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 CH3OS(O)Cl in situ, might escape from the original cage to yield isolated CH3OSO radicals. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3696894]