title: Wheland intermediates: an ab initio valence bond study.
abstract: The traditional resonance model for electrophilic attacks on substituted aromatic rings is revisited using high level valence bond (VB) calculations. A large π-donation is found in the X = NH(2) case and a weaker one for the X = Cl case, not only for ortho and para isomers but also for the meta case, which can be explained by considering five (not three) fundamental VB structures. No substantial π-effect is found in the X = NO(2) case, generally viewed as π-attractive.
authors.affiliation: UPMC Univ Paris 06, UMR 7616, Laboratoire de Chimie Théorique, case courrier 137, 4, place Jussieu, F-75252 Paris Cedex 05, France.
authors.forename: Mélodie
authors.initials: M
authors.lastname: Hadzic
authors.forename: Benoît
authors.initials: B
authors.lastname: Braïda
authors.forename: François
authors.initials: F
authors.lastname: Volatron