[C2H4OS]·+ Radical cations derived from alkyl thioformates: Tandem mass spectrometry and molecular orbital calculations

Abstract

[C2H4OS]·+ radical cations have been generated upon dissociative ionization of some S-alkyl and O-alkyl thioformates and characterized by tandem mass spectrometry methodologies and molecular orbital calculations at the UQCISD(T)/6-311++G(d,p)//UMP2/6-31G(d,p) level. Use of a combination of collisional activation (high and low energy translational energies), neutralization- reionization and ion-molecule reaction experiments performed in a single instrument, combining different magnetic and electric sectors and a radiofrequency-only quadrupole collision cell, led to the identification of distonic radical cations and ion-molecule complexes such as HC+(OH)SCH2· and CH3S·+(H) ⋯ CO, beside ions having a more classical structure, HC(=S)OCH3·+ and HC(=O)SCH3·+. Experimental evidence for the existence of the isomeric distonic HC+(SH)OCH2· species has not been found, but calculations of the related [C2H4OS]·+ potential energy surface suggest that the latter ion is stable and likely to play a role in the fragmentation processes.