Abstract: The gas-phase reaction mechanism of allyl anion with N2O was investigated at the MP2/6-31G(d,p) level of the MP2 theory. The single-point energies have also been refined at the CCSD(T)/6-31G(d,p) level to get more accurate energies using the MP2/6-31G(d,p) optimized geometries. The computational results indicated that the reaction involved three reaction pathways to produce cis-vinyl-diazomethyl anion, trans-vinyl-diazomethyl anion, and allenyl anion. The major competition channels of the reaction which produced cis-vinyl-diazomethyl anion, and trans-vinyl-diazomethyl anion all involved two steps of α-H migration. Furthermore, all these rate-determing steps are the second α-H migration and the barriers are 89.79 and 97.93 kJ·mol-1, respectively. Distinctly, allenyl anion was formed through one α-H and one β-H migration and its rate-determing step was the rotation of the N10—O11 and N9—C3 bonds around N—N bond. The rate coefficients of the rate-determining step of all the reaction channels have also been calculated using statistic thermodynamics and conventional transition state theory at 298 K.

Key words: Allyl anion, reaction mechanism, Second-order Moller-Plesset perturbation theory (MP2), Transition state theory