科研之友
微信
新浪微博
Facebook
分享链接
摘要
The spin-forbidden reaction mechanism of Ta+(F-5, 5d(3)6s(1)) with C2H6 on the quintet, triplet, and singlet potential energy surfaces has been investigated at the density functional level of theory using the hybrid exchange correlation functional B3LYP. Crossing points between the potential energy surfaces are located using different methods, and possible spin inversion processes are discussed by means of spin-orbit coupling (SOC) calculations. As a result, there is a crossing seam from 3-5CPmin to 3-5CPmax between the quintet and the triplet state surfaces. The reacting system will change its spin multiplicities from the quintet state to the triplet state near this crossing seam, leading to a significant decrease in the barrier height of (5)Ts1-2 from 34.0 to 15.1 kcal/mol, and then move on the triplet potential energy surface as the reaction proceeds. The minimum energy crossing point (3-5MECP) is located by using the methods of Harvey et al. The probability values of the single (P-1(Isc)) and double (P-2(Isc)) passes estimated at 3-5MECP are approximately 9.39 x 10(-2) and 0.17, respectively. After the C-H insertion intermediate 2, two distinct reaction paths have been found, a H-2 elimination path and a CH4 elimination path. The former is found to be the lowest energy path on the triplet PES, while a high C-C insertion barrier of the latter prevents observation of this species under thermal conditions. These conclusions are consistent with the experimental observations.
