Bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation: a theoretical validation of a bishomoaromatic radical cation intermediate.
[structure: see text] A natural bond orbital analysis of the distonic bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation interprets its structure and radical character by a three-center two-electron bond between C2, C3, and C7 (a bishomoaromatic stabilization) and a singly occupied orbital on C5, n(5). Moreover, B3LYP/6-311+G(d,p) ESR parameters, which agree excellently with experiment, are interpreted in terms of spin polarization in the natural hybrids of sigma(C5-H5), and a dual hyperconjugative effect involving n(5), sigma(C1-H1a), sigma(C1-H1b), and antibonding counterparts.
Larsson
Per-Erik
PE
Department of Quantum Chemistry, Uppsala University, S-751 20 Uppsala, Sweden. per-erik.larsson@kvac.uu.se
Salhi-Benachenhou
Nessima
N
Lunell
Sten
S