Generation and reactivity of gas-phase phenyloxenium ion

Abstract

Phenyloxenium ion (POI) is an important intermediate in organic reactions, however, its generation and reactivity have not been extensively investigated. In this study, POI is produced in the gas phase by electrospray ionization tandem mass spectrometry (ESI-MS/MS), isolated for gas phase ion-molecule reactions, and used theoretical calculations to reveal mechanisms to those reactions. It forms adduct ions with H2O, methanol, ethanol, benzene, and toluene, although the structures of the adduct ions are not well-resolved. In contrast, ortho-cyclization with nitriles has been verified by the reaction with acetonitrile and theoretical calculation. Further, Hydride transfer reaction during the reaction with tetrahydrofuran in the gas phase led to experimental values of the hydride affinity and electronic state of POI. Electron transfer studies revealed that the ionization potential of phenoxy radical locates in the range of 8.01–9.19 eV, in line with the calculated value of 8.60 eV for the singlet state POI.