Nitronium ion

The Nitronium ion, NO₂⁺, is not stable enough to exist in normal conditions, but it is used extensively in the nitration[?] of other substances. The ion is created in situ by mixing sulphuric acid and nitric acid according to the equilibrium:

H₂SO₄ + HNO₃ ↔ HSO₄^- + NO₂⁺ + H₂O

The nitronium ion also exists in the solid form of the nitrogen oxide N₂O₅, which is an ionic solid formed from nitronium and nitrate ions. Its liquid and gaseous forms, however, are molecular and do not contain nitronium ions.