Title

Barrierless Reactions of Three Benzonitrile Radical Cations with Ethylene

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.

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Link to publisher version (DOI)

http://dx.doi.org/10.1071/CH19606