Definition of cyclohexadienyl cations

A subclass of arenium ions.

arenium ions:Cations derived formally by the addition of a hydron or other cationic species to any position of an arene. E.g. C6H7+, benzenium. Cf. aryl cations.

The term includes:

1. Arenium sigma-adducts (Wheland intermediates) such as (which are considered to be intermediates in electrophilic aromatic substitution reactions) and other cyclohexadienyl cations.

2. Arenium pi-adducts, such as

GTPOC [sigma] -adduct (sigma adduct), [pi] -adduct (pi adduct).