in Fundamentals of Gas-Phase Ion Chemistry, ed. K.R. Jennings; Kluwer, Dordrecht 1991; p 379
The formation of intermediate ion-neutral complexes in unimolecular dissociation reactions can be confirmed when the life-time of such intermediates is sufficiently long. Evidence to confirm the presence of complexes prior to the elimination of alkane molecules from alcohol and ether molecular ions comes from specific hydrogen atom exchange and from kinetic energy release measurements.
The properties of the intermediate complexes formed during dissociation reactions are closely related to those of similar complexes formed by bimolecular reactions. Addition of alkyl radicals to protonated carbonyl groups occurs in [alkyl-radical/oxonium-ion] complexes under both unimolecular and bimolecular conditions. The unimolecular loss of alkane molecules from these complexes exhibit unusually large primary and secondary isotope effects.