Loss of HCN from the Pyrimidine Molecular Ion: A Computational Study

摘要

The potential energy surface (PES) for the loss of HCN from the pyrimidine molecular ion has been explored using quantum chemical calculations. Possible reaction pathways to form five C3H3N+• isomers have been obtained with Gaussian 4 model calculations. The rate constant for the HCN loss and the product branching ratio have been calculated using the Rice-Ramsperger-Kassel-Marcus theory on the basis of the obtained PES. The resultant rate constant agrees with the previous experimental result. By a kinetic analysis, it is proposed that the formation of CH=CHC≡NH+• is favored near the dissociation threshold, while the formation of CH=CHN≡CH+• is favored at high energies.