Infrared chemiluminescence studies of H + BrCN and H abstraction by CN reactions. Importance of the HNC channel

Abstract

The H + BrCN reaction and the H abstraction reactions from HI, H₂S, PH₃, SiH₄, CH₃OCH₃, c-C₅H₁₀ and C(CH₃)₄ by CN were studied by infrared chemiluminescence in a fast flow reactor. From the dependence of the HCN and HNC emission intensities on temperature, activation energies of 5.2 ± 0.4 and 7.5 ± 0.8 kcal mol^-1 were assigned for the HCN and HNC channels from the H + BrCN reaction. The anharmonicity constant, X_3,3 for HNC, was determined to be 66 cm^-1. All reactions yielded HCN with an inverted vibrational distribution in v₂ along with v₂ excitation and <f_v> = 0.4-0.5. The abstraction reaction PH₃ and HI produced HNC (v₃,≥ 1) with HNC/HCN ratios of ≥ 0.02 and ≥ 0.43, respectively.