Kinetics and mechanism of the CH + N₂ reaction. Temperature- and pressure-dependence studies and transition-state-theory analysis

The reaction CH + N₂ → products was studied at 297 K at total pressures between 25 and 787 torr. The second-order reaction rate constant was found to be pressure dependent, varying by a factor of 9.6 in this range. This reaction was also studied in the range 297-675 K at 100-torr total pressure. The rate constant decreases with increasing temperature and cannot be adequately described by a linear fit in this range. Transition-state-RRKM-theory calculations for the reaction proceeding through a long-lived intermediate, HCN₂, successfully describe the data. Stabilization of the adduct is the primary reaction channel at lower temperatures while metathesis dominates above 1000 K. These calculations provide a consistent description of these and previous data from flame studies.