A comparison of the unimolecular decomposition pathways of some C7 and C8 ions in the gas phase

Abstract [CnH2n−3]+ and [CnH2n−4]+·(n = 7, 8) ions have been generated in the mass spectrometer from CnH2n−3 Br (n = 7, 8) precursors and from two steroids. The relative abundances of competing ‘metastable transitionss’ indicate (partial) isomerization to a common structure (or mixture of structures) prior to decomposition in most examples of all four types of ions. In contrast, [C8H10O]+· and [C8H12O]+· ions, generated from different sources as molecular ions and by fragmentation of steroids, do not decompose through common‐intermediates.