A Theoretical Study on the Reaction Mechanism of the Gas-Phase Decomposition of NO by NH₃⁺ and NH₄⁺

High level ab initio calculations have been performed to study the mechanism of NO decomposition by NH 3 + and NH 4 + in the gas phase, NH 3 + + NO → N 2 + H 3 O + and NH 4 + + NO → N 2 H + H 3 O + . The density functional theory was used to search for possible reaction pathways. The multiconfigurational second-order perturbation (CASPT2) method is applied to the most energetically favorable pathways to obtain more accurate energy diagrams. NO reacts with NH 3 + and NH 4 + by producing nitrogen−nitrogen bound complexes and by donating protons/hydrogens to the O atom to weaken the N−O bond and to tighten the N−N bond. Maximum activation energies for these reactions were estimated as 55.3 and 77.3 kcal/mol.