Evidence for ion‐neutral complex‐mediated reactions well above the threshold for dissociation of the complex

Abstract

The possibility that ion-neutral complex-mediated eliminations occur well above the threshold for simple dissociation of the partners in the complex was explored. This was accomplished by determining whether daughter ions of probable complex-mediated dissociations undergo metastable decompositions. All six complex-mediated decompositions examined formed metastable ions. Therefore, a very small fraction of ion-neutral complex-mediated fragmentations may occur several hundred kJ mol-above the threshold for dissociation of the partners.

Formation of the 3-Pentanone ion from ionized propyl propanoate through Ion-Neutral complexes

“…In previous studies of alkane eliminations [12,16,24], PIE curves reached plateaus a few tenths of an electronvolt above the onset for simple loss of the alkyl radical, demonstrating that complexmediated alkane eliminations are largely confined to a narrow energy range near threshold. However, small portions of alkane eliminations may occur up to very high energies [25]. If Scheme III were correct, the PIE curve for 3 should become horizontal within a few tenths of an electronvolt of threshold.…”