Mechanism and Stereoselectivity of the Elementometalation Process of Activated Alkyne RCCR(RCO₂Me) by Cp₂TaH₃

Abstract

The elementometalation process is a fundamental chemical step in several catalytic cycles. In this work, density functional theory computations have elucidated the detailed elementometalation mechanism of activated alkyne RCCR(RCO2Me) by Cp2TaH3 and rationalized the selectivity in experimental findings. The calculated results show that in the formation process of (E)‐olefin monohydride((E)‐Pro), the Gibbs free energy barrier is low and the entire reaction is spontaneous and exothermic; thus, (E)‐Pro can be formed easily. The formation of (Z)‐η2‐olefin monohydride complex ((Z)‐Pro) is difficult due to its high Gibbs free energy barrier. The formation process (E)‐Pro consists of the following five steps: hydride H1‐shift, conformational isomerism 1, hydride H2‐shift, conformational isomerism 2, and olefin coordination process. Topological analysis shows that there is a five‐membered ring plane structure in the reaction pathway and that the final product (E)‐Pro belongs to a typical η2‐olefin monohydride complex. Our calculated results provide an explanation for experimental observations and useful insights for further development of olefin functionalization. © 2019 Wiley Periodicals, Inc.

Stereoselectivity and nonmigratory insertion mechanism of dimethylacetylene dicarboxylate into metallocene‐hydride of Cp2M(L)H [Cp =η5‐C5H5; M = Nb, V; L = CO, P (OMe)3]: A DFT study

“…It is worth noting that the H1 atom is added to the C1 atom rather than the C2 atom, which is consistent with the experimental structure. [29] In this process, the transferred H1 belongs to a hydride H, and the H1 atom in the Nb-H1 bond shows a significant negative character; [56,57] thus, the H1 shift belongs to the hydride-H shift.…”