Exploring the Multiple Reaction Pathways for the H + cyc-C₃H₆ Reaction

Reaction pathways for the hydrogen atom plus cyclopropane (cyc-C3H6) reaction are studied using an
extrapolated coupled-cluster/complete basis set (CBS) method based on the cc-pVDZ, cc-pVTZ, and cc-pVQZ basis sets. For this activated reaction, results reveal two reaction mechanisms, a direct H-abstraction
and a H-addition/ring-opening. The hydrogen-abstraction reaction yields the H2 and cyclopropyl (cyc-C3H5)
radical products. The vibrationally adiabatic ground-state (VAG) barrier height is predicted to be 13.03 kcal/mol. The isomerization barrier height from the product cyclopropyl to allyl radical is 21.98 kcal/mol via a
cyc-C3H5 ring-opening process. In addition, the H-addition and ring-opening mechanism will lead to an n-C3H7
radical, which can result in a variety of products such as CH3 + C2H4, H + CH3CHCH2, and H2 + C3H5, etc.
The VAG barrier height of the H-addition reaction is 16.49 kcal/mol, which is slightly higher than that of the
direct H-abstraction reaction. Although the H + cyc-C3H6 → CH4 + CH2CH reaction is exoergic by 11.90
kcal/mol, this reaction is unlikely due to a high barrier of 43.05 kcal/mol along the minimum energy path.