title: Bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation: a theoretical validation of a bishomoaromatic radical cation intermediate.
abstract: [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.
authors.affiliation: Department of Quantum Chemistry, Uppsala University, S-751 20 Uppsala, Sweden. per-erik.larsson@kvac.uu.se
authors.forename: Per-Erik
authors.initials: PE
authors.lastname: Larsson
authors.forename: Nessima
authors.initials: N
authors.lastname: Salhi-Benachenhou
authors.forename: Sten
authors.initials: S
authors.lastname: Lunell