Amine radical cations: an electron spin resonance study of cations generated by radiolysis
- 1 January 1984
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 9,p. 1551-1557
- https://doi.org/10.1039/p29840001551
Abstract
Amine radical cations have been generated by exposing dilute solutions of amines to 60Co γ-rays at 77 K. They are well characterised by their e.s.r. spectra, the method and interpretation being established by showing that the e.s.r. data for Me3Ṅ+ cations are identical with literature values. Results for the triethylammonium cation show that the β-protons do not occupy the most favourable sites for maximum hyperconjugation, in contrast with other radical cations. This is explained in terms of steric factors, and an equilibrium between two preferred conformations. 1,1-Diamines, R2NCH2NR2, give cations having localised structures, R2Ṅ[graphic omitted]H2NR2, rather than the delocalised structure adopted by acetal cations. Possible evidence for weak N–N bonding and delocalisation is adduced for NN′-dimethylpiperazine cation, but we confirm that the cation of triethylenediamine has a truly delocalised σ* structure. There is no tendency for R3N+˙ cations to react with neutral amines to give (R3N[graphic ommitted]NR3)+ dimer cations, in marked contrast with results for corresponding trialkylphosphine systems.Keywords
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