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The reaction of N2H4 with OH has been investigated by quantum chemical methods. The results show that hydrogen abstraction mechanism is more feasible than substitution mechanism thermodynamically. The calculated rate constants agree with the available experimental data. The calculated results show that the variational effect is small at lower temperature region, while it becomes significant at higher temperature region. On the other hand, the small-curvature tunneling effect may play an important role in the temperature range 220-3000 K. Moreover, the calculated rate constants show negative temperature dependence at the temperatures below 500 K, which is in accordance with Vaghjiani's report that slightly negative temperature dependence is found over the temperature range of 258-637 K. The mechanism of the major product (N2H3) with OH has also been investigated theoretically to understand the title reaction thoroughly. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [ABSTRACT FROM AUTHOR]

The reaction of H radical with C2H5CN has been studied using various quantum chemistry methods. The geometries were optimized at the B3LYP/6-311+G(d,p) and B3LYP/6-311++G(2d,2p) levels. The single-point energies were calculated using G3 and BMC-CCSD methods based on B3LYP/6-311++G(2d,2p) geometries. Four mechanisms were investigated, namely, hydrogen abstraction, C-addition/elimination, N-addition/elimination and substitution. The kinetics of this reaction were studied using the transition state theory and multichannel Rice-Ramsperger-Kassel-Marcus methodologies over a wide temperature range of 200–3000 K. The calculated results indicate that C-addition/elimination channel is the most feasible over the whole temperature range. The deactivation of initial adduct C2H5CHN is dominant at lower temperature with bath gas H2 of 760 Torr; whereas C2H5+HCN is the dominant product at higher temperature. Our calculated rate constants are in good agreement with the available experimental data. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [ABSTRACT FROM AUTHOR]