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A theoretical study of α‐substituted cyclopropyl and isopropyl radicals
Author(s) -
Lien M. H.,
Hopkinson A. C.
Publication year - 1985
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540060403
Subject(s) - radical , isopropyl , chemistry , substituent , crystallography , ab initio , medicinal chemistry , stereochemistry , computational chemistry , organic chemistry
The structures of α‐ X ‐cyclopropyl and α‐ X ‐isopropyl radicals ( X = H, CH 3 , NH 2 , OH, F, CN, and NC) are reported at the RHF 3‐21G level of theory. The isopropyl radicals are pyramidal with out‐of‐plane angles varying from 12° ( X = CN) to 39° ( X = NH 2 ), and barriers to inversion ranging from 0.4 kcal/mol ( X = H) to 4.0 kcal/mol ( X = NH 2 ). The cyclopropyl radicals have larger out‐of‐plane angles, from 39.9° ( X = CN) to 49.4° ( X = NH 2 ), and their barriers to inversion, which increase with the inclusion of polarization functions, vary from 5.5 kcal/mol ( X = H) to 16.7 kcal/mol ( X = F). In both types of radicals the amino group is the most stabilizing substituent, while the α‐fluoro has little effect. The β‐fluoro group is weakly destabilizing in the cyclopropyl radical. The strain energies of the cyclopropyl radicals (36–43 kcal/mol) are compared with those of similarly substituted anions, cations, and cyclopropanes.