A nitrenium ion (also called: aminylium ion) in organic chemistry is a reactive intermediate based on nitrogen with both an electron lone pair and a positive charge and with two substituents (R2N+). Nitrenium ions are isoelectronic with carbenes, and can exist in either a singlet or a triplet state. The parent nitrenium ion, NH2+, is a ground state triplet species with a gap of 30 kcal/mol to the lowest energy singlet state. Conversely, most arylnitrenium ions are ground state singlets. Certain substituted arylnitrenium ions can be ground state triplets, however. Currently, nitrenium ions see heavy study in the groups of Matt Platz (Ohio State), Michael Novak (Miami), and Daniel Falvey (University of Maryland).
Aryl nitrenium ions are currently investigated because of their involvement in certain DNA damaging processes. These intermediates can have microsecond or longer lifetimes in water. They can also be exploited for useful synthetic processes.
Nitrenium ions are also intermediates in organic reactions; for instance, the Bamberger rearrangement. They can also act as electrophiles in electrophilic aromatic substitution.
Phenylnitrenium ion reaction with guanine, DFT energies for 22 isomeric adducts.
The term imidonium ion with the same meaning, is now obsolete.