Rearrangements and fragmentations of [C2H5S]+ ions

C₂H₅S]⁺ ions (m/e 61) with different initial structures were generated in the mass spectrometer from twelve precursor ions. Abundance ratios of competing metastable ion decompositions were used to determine whether these ions decompose through the same or different reaction channels. It was concluded that all C₂H₅S]⁺ ions isomerize to a common structure or mixture of structures prior to decomposition in the first field free region. From ¹³C labelling experiments it was concluded that C₂H₅S]⁺ ions generated from the molecular ions of 2-propanethiol-2-¹³C], partially rearrange to a symmetrical structure before decomposition to CHS]⁺ and CH₄, whereas in C₂H₅S]⁺ ions generated from the the molecular ions of 1,2-bis-(thiomethoxy-¹³C]) ethane, the two carbon atoms become fully equivalent before CH₄ loss occurs.