Quasiclassical Trajectory Calculations of the N(²D) + H₂O Reaction Elucidating the Formation Mechanism of HNO and HON Seen in Molecular Beam Experiments

The N­(²D) + H₂O is a reaction with competitive product channels, passing through several intermediates. Dynamics of this reaction had been investigated by two of the present authors at two collision energies, <i>E</i>_c, using the crossed molecular beams mass spectrometric method (Faraday Discuss. 2001, 119, 27−49). The complicated mechanism of this reaction and puzzling results encouraged us to investigate the reaction in a joint experimental/theoretical study. Quasiclassical trajectory (QCT) calculations on an ab initio potential energy surface describing all channels of the title reaction are done with a focus on the N/H exchange channels. Interesting results of QCT calculations, in very good agreement with experimental data, reveal subtle details of the reaction dynamics of the title reaction to HNO/HON + H exit channels by disentangling the different routes to formation of the two possible HNO/HON isomers and therefore assisting in a critical manner the derivation of the reaction mechanism. Results of the present study show that the nonstatistical HNOH intermediate governs exit channels; therefore, the HON channel is as important as that of HNO. The study also confirms that the H₂ + NO molecular channel is negligible even though the barrier to its formation is calculated to be well below the reactant asymptote