Issue 32, 2016

The methylsulfinyl radical CH3SO examined

Abstract

Methylsulfinyl radical, a key intermediate in marine atmospheric chemistry, plays a central role in the oxidation of dimethyl sulfide. CH3SO 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 [X with combining tilde] 2A′′ and à 2A′ states are quite different with S–O distances of 1.499 and 1.652 Å, respectively. The [X with combining tilde] 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 CH3OO. The CH3SO barrier to internal rotation is 0.92 kcal mol−1. The unknown [X with combining tilde] 2A′′ torsional vibrational frequency τ is predicted to be 142 cm−1 (harmonic) and 128 cm−1 (anharmonic). Our predictions of the à 2A′ excited state vibrational frequencies are the first to be reported.

Graphical abstract: The methylsulfinyl radical CH3SO examined

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
27 Jun 2016
Accepted
20 Jul 2016
First published
21 Jul 2016

Phys. Chem. Chem. Phys., 2016,18, 22293-22299

The methylsulfinyl radical CH3SO examined

M. L. Estep and H. F. Schaefer III, Phys. Chem. Chem. Phys., 2016, 18, 22293 DOI: 10.1039/C6CP04505G

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