Recent radiolytic studies on the mechanism of gas-phase ionic reactions

Recent mechanistic applications of radiolytic techniques to gas-phase ion-molecule reactions are reviewed. In particular, attention is focused on the following typical research areas: (i) structural and stereochemical characterization of gaseous ions, and study of their isomerization in a wide pressure range, (ii) stereochemical course of selected ion-molecule reactions, (iii) mechanistic features of gas-phase aromatic substitution, in particular evaluation of the substrate and positional selectivity of gaseous cations, and (iv) competition between proton-transfer and condensation reactions of gaseous cations with n-type nucleophilic centers. The results reviewed underline the mechanistic value of current radiolytic techniques, whose application does extend to the gas phase the degree of structural and stereochemical specificity typical of solution-chemistry studies. (author)