We report the observation of the CH 3S(O)CH - and CH 3S(O)CH -·H 2O carbene anions formed upon overall H 2 + abstraction from dimethyl sulfoxide by O -. Photoelectron spectroscopy reveals singlet and triplet carbenes for the remaining neutral, with the singlet state assigned as the ground state. Although some formation of the distonic CH 2S(O)CH 2 - radical anion is also expected, no conclusive evidence of the presence of this isomer is found. The photoelectron spectrum of HCSO - is also reported for the first time. Photofragmentation of CH 3S(O)CH - with 532 nm light reveals two main types of anionic products: a dominant HCSO - fragment, resulting from methyl elimination, and a less intense SO - product. For the monohydrated anion, an additional SO - · H 2O fragment is observed. Intriguingly, both the SO -·H 2O and SO - products are produced with much higher yields in the fragmentation of CH 3S(O)CH - · H 2O, compared to the SO - yield from the dissociation of the bare CH 3S(O)CH- anion. Two possible pathways are proposed as likely mechanisms for the SO --based photoproducts, both involving a photoinduced intramolecular rearrangement and the formation of a C-C bond.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry