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Investigation of Benzimidazoles. 6 —transmission of substituent effects in dianion radicals of 2‐substituted 5(6)‐nitrobenzimidazoles studied by ESR spectroscopy
Author(s) -
Lopyrev V. A.,
Larina L. I.,
Vakul'skaya T. I.,
Shibanova E. F.,
Titova I. A.,
Voronkov M. G.
Publication year - 1985
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260230506
Subject(s) - chemistry , substituent , radical , nitrobenzene , acetonitrile , ring (chemistry) , benzene , benzimidazole , photochemistry , spectroscopy , hyperfine structure , medicinal chemistry , organic chemistry , physics , quantum mechanics , catalysis
The substituent effects in dianion radicals of fourteen 2‐substituted 5(6)‐nitrobenzimidazoles, electrochemically generated in acetonitrile, were studied by ESR. It was found that the substituent influence on the nitro group is transmitted with approximately equal contributions from the inductive and resonance components, independently of the pairs of the σ I σ R , σ I σ R o ,σ I σ R + and ℱℛ substituent constants used. The radical stabilization constant σ contributes much to the correlation of the hyperfine splitting constants of H‐6 and the heterocyclic nitrogen atoms. The transmission through the benzimidazole ring in dianion radicals of nitrobenzimidazoles is half that of the benzene ring in anion radicals of para ‐substituted nitrobenzenes.