The methylsulfinyl radical CH3SO examined. Issue 32 (26th July 2016)

• Record Type: Journal Article
• Authors: Estep, Marissa L.; Schaefer III, Henry F.
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 32(2016)
• Page Start: 22293
• Page End: 22299
• Publication Date: 2016-07-26
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp04505g
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Our computational investigations broaden the scope of currently available experimental results on the methylsulfinyl radical, a key atmospheric species. Abstract : Methylsulfinyl radical, a key intermediate in marine atmospheric chemistry, plays a central role in the oxidation of dimethyl sulfide. CH3 SO has been extensively studied here with ab initio quantum mechanical methods, with methods as complete as CCSDT(Q) in conjunction with basis sets as large as cc-pV(5+d)Z. In this research, we report high-level computations for the ground and first excited electronic states of the methylsulfinyl radical. The structures of the X̃ 2 A′′ and à 2 A′ states are quite different with S–O distances of 1.499 and 1.652 Å, respectively. The X̃ to à adiabatic energy difference is predicted to be 45.1 kcal mol −1, compared to 21.1 kcal mol −1 for the analogous well-characterized methylperoxy radical CH3 OO. The CH3 SO barrier to internal rotation is 0.92 kcal mol −1 . The unknown X̃ 2 A′′ torsional vibrational frequency τ is predicted to be 142 cm −1 (harmonic) and 128 cm −1 (anharmonic). Our predictions of the à 2 A′ excited state vibrational frequencies are the first to be reported.