DFT Study on Mechanism of Olefin Hydroalumination by XAlBu<i>ⁱ</i>₂ in the Presence of Cp₂ZrCl₂ Catalyst. I. Simulation of Intermediate Formation in Reaction of HAlBu<i>ⁱ</i>₂ with Cp₂ZrCl₂

Abstract

The mechanism of intermediate formation in the reaction of HAlBui2 with Cp2ZrCl2 has been studied by DFT calculations. Stationary points have been localized on the potential energy surface of the reaction; enthalpy has been calculated for each of them at T = 203 K. It was shown that the thermodynamically probable way of the process includes formation of a bridge bimetallic complex [Cp2ZrCl2·HAlBui2], which with dissociation gives Cp2ZrHCl. The subsequent coordination of Cp2ZrHCl with HAlBui2 provides the intermediate [Cp2ZrHCl·HAlBui2], which dimerizes into an experimentally observed complex [Cp2ZrH2·ClAlBui2]2. The competing stage of [Cp2ZrHCl·HAlBui2] interaction with HAlBui2 yields complex [Cp2ZrH2·ClAlBui2·HAlBui2], which shows low activity in the olefin hydrometalation. As a result, the scheme of the intermediates’ formations and transformations in the reaction of HAlBui2 with Cp2ZrCl2 was proposed.