Detailed mechanisms on insertion of cis-2-butene into the Zr–H bond of Cp2ZrH2: A DFT study

The detailed mechanisms for reaction of Cp2ZrH2 with cis-2-butene were explored with the aid of density functional theory calculations. Two possible pathways for olefin insertion into the Zr–H of Cp2ZrH2 were proposed. One is the side-insertion and the other is the central-insertion. The central-insertion is theoretically predicted to be more favorable kinetically than the side-insertion. It is revealed that formation and cleavage of Zr⋯H–C agostic interaction and β-hydrogen elimination are requisite steps in addition to the olefin insertions. The side-agostic and the central-agostic interactions are found to be involved in some intermediates. The former agostic is less stable than the latter, which plays a role in describing which path is preferred.