Structure and fragmentations of [C3H7S]+ ions

The principal fragmentation reactions of metastable C₃H₇S]⁺ ions are loss of H₂S and C₂H₄. These reactions and the preceding isomerizations of C₃H₇S]⁺ ions with six different initial structures were studied by means of labelling with ¹³C or D. From the results it is concluded that the loss of H₂S and C₂H₄ both occur at least mainly from ions with the structure CH₃CH₂CH? SH]⁺ or from ions with the same carbon sulfur skeleton, with the exception of the ions with the initial structure CH₃CH₂S? CH₂]⁺, which partly lose C₂H₄ without a preceding isomerization. For all ions, more than one reaction route leads to CH₃CH₂CH?SH]⁺. It is concluded that the loss of H₂S is at least mainly a 1,3-elimination from the CH₃CH₂CH?SH]⁺ ions. Both decomposition reactions are preceded by extensive but incomplete hydrogen exchange.