DFT and Ab Initio Study on Mechanism of Olefin Hydroalumination by XAlBui2 in the Presence of Cp2ZrCl2 Catalyst. II. Olefin Interaction with Catalytically Active Centers

The mechanism of alkene hydroalumination by HAlBui2 catalyzed with Cp2ZrCl2 has been studied computationally at the DFT and MP2 levels of theory. The mechanism involves several catalytic cycles with the following stages: active center formation, alkene hydrozirconation, transmetalation, and regeneration of key intermediates. The complexes Cp2ZrHCl, [Cp2ZrH2·ClAlBui2], [Cp2ZrH2·HAlBui2·ClAlBui2], and [Cp2ZrH2·(HAlBui2)2] are considered as active species of the catalytic process. It has been shown that the hydrometalation ability of the complexes decreases in the series Cp2ZrHCl > [Cp2ZrH2·ClAlBui2] > [Cp2ZrH2·HAlBui2·ClAlBui2] > [Cp2ZrH2·(HAlBui2)2]; this is caused by an increase in the number of Zr–H–Al bridge bonds as a result of consecutive HAlBui2 addition. For comparison, thermodynamic and activation parameters of a noncatalytic propene reaction with HAlBui2 were calculated.