Barrierless Reactions of Three Benzonitrile Radical Cations with Ethylene

Authors

Oisin Shiels, University of WollongongFollow
Patrick Kelly, University of WollongongFollow
Stephen Blanksby
Gabriel da Silva
Adam J. Trevitt, University of WollongongFollow

RIS ID

143429

Publication Details

Shiels, O., Kelly, P., Blanksby, S., da Silva, G. & Trevitt, A. (2020). Barrierless Reactions of Three Benzonitrile Radical Cations with Ethylene. Australian Journal of Chemistry,

Abstract

© 2020 CSIRO. Reactions of three protonated benzonitrile radical cations with ethylene are investigated. Product branching ratios and reaction kinetics, measured using ion-trap mass spectrometry, are reported and mechanisms are developed with support from quantum chemical calculations. Reactions proceed via pre-reactive van der Waals complexes with no energy barrier (above the reactant energy) and form radical addition and addition-elimination product ions. Rate coefficients are 4-dehydrobenzonitrilium: 1.72 ± 0.01 × 10-11 cm3 molecule-1 s-1, 3-dehydrobenzonitrilium: 1.85 ± 0.01 × 10-11 cm3 molecule-1 s-1, and 2-dehydrobenzonitrilium: 5.96 ± 0.06 × 10-11 cm3 molecule-1 s-1 (with ±50 % absolute uncertainty). A ring-closure mechanism involving the protonated nitrile substituent is proposed for the 2-dehydrobenzonitrilium case and suggests favourable formation of the protonated indenimine cation.