Theoretical Study of the Rate Coefficients for CH3NHNH2+NO2 and Related Reactions

The kinetics and mechanisms of H atom abstraction reactions from CH3NHNH2 by NO2 (R1) and related reactions have been investigated theoretically by using B97X-D and CCSD(T)-F12 quantum chemical calculations and the steady-state unimolecular master equation analysis based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory. For reaction (R1), both dissociation and isomerization steps between intermediate complexes were found to be important for the distribution of the dissociated bimolecular products. The dominant products of (R1) were found to be cis-CH3NHNH and HONO at lower temperature. The branching ratios for CH3NNH2 formation paths increased with increasing temperature. On the same reaction potential energy surface, six reactions including isomerization reactions between CH3NNH2 and cis-/trans-CH3NHNH catalyzed by HONO were suggested to compete with the reverse reaction of (R1). The temperature- and pressure-dependent rate expressions are proposed for kinetic modeling.