title: Large hyperconjugation in strained systems.
abstract: Carbocations can appear as transient species, for instance, in elimination reactions and various rearrangements. Hyperconjugation (or conjugation) can then stabilize the cationic character and form a partial π bond. The effect of the electronic delocalization from strained substituents to a carbocation part was calculated. Very large hyperconjugation was found, sometimes more than 80 kcal mol(-1) , which is much larger than typical conjugation effects (56 kcal mol(-1) for the allyl cation).
authors.affiliation: Aix Marseille Université, CNRS, Centrale Marseille, ISM2 UMR 7313, 13397, Marseille (France), Fax: (+33) 491-28-82-34.
authors.forename: Julien
authors.initials: J
authors.lastname: Racine
authors.forename: Stéphane
authors.initials: S
authors.lastname: Humbel
keywords: carbocations; charge transfer; density functional calculations; hyperconjugation; strained molecules