The geometry optimization and vibrational frequency analysis of all the chemical species and transition states (TS) were performed with B3LYP along with a basis set of 6-311 +G(d, p), and Gaussian 09 software was used to perform the study. 
Gaussian 09
The rate constants were calculated by KiSThelP according to the conventional transition state theory (TST), and the Wigner method was applied to acquire the tunneling correction factors. 
KiSThelP