A Theoretical Study of the Reaction Mechanism and Rate Constant of C4H ($$ {{\tilde{\text{x}}}}^{2} {\varsigma^{ + }} $$X~2Σ+) + C2H6

Theoretical investigations have been carried out on the mechanisms and kinetics of the reaction of linear butadiynyl radical with ethane at the CCSD(T)/aug-cc-pVTZ//ωB97X-D/6-311++G(3df,2p) level. Four hydrogen abstraction channels (M1a, M1b, M2a and M2b) were investigated. The calculated results indicate that two competitive channels M1a and M1b are the predominant mechanisms, while M2a and M2b are unfavorable due to the higher barriers. The canonical variational transition state theory (CVT) with the small-curvature tunneling correction (SCT) was utilized to calculate the rate constants for M1a and M1b. The reactant side wells along the two reaction paths (M1a and M2b) were found and considered in chemical kinetic calculations. The three-parameter rate constant expressions are fitted over a wide temperature range of 145–1000 K.