What is "halonium ion"

n. (context chemistry English) Any cation of the general formula R₂X⁺, where X is any halogen.

A halonium ion in organic chemistry is any onium compound (ion) containing a halogen atom carrying a positive charge. This cation has the general structure R–X–R where X is any halogen and R any organic residue and this structure can be cyclic or an open chain molecular structure. Halonium ions formed from fluorine, chlorine, bromine, and iodine are called fluoronium, chloronium, bromonium, and iodonium, respectively.