Effect of Donors on the Activation Mechanism in Ziegler–Natta Catalysis: A Computational Study

Abstract Full quantum chemical calculations, using density functional theory (DFT), have been conducted to explain the effect of donors on the “activation mechanism” in the Ziegler–Natta (Z–N) catalyst system. In the activation mechanism, the inactive Ti IV Cl 4 catalyst converts into the active Ti III Cl 2 Et catalyst with the help of the AlEt 3 present in the system. The donors that have been considered in this study are: ethyl benzoate ( eb ), two representative diether cases, a phthalate donor, and a silyl ester donor. The results indicate that eb and the diether donor cases donor have a negative effect on the barriers for the activation mechanism. However, the eb donor can be displaced from the MgCl 2 surface by AlEt 3 , which matches experimental observations. For the phthalate, silyl ester and TiCl 3 –OC 4 H 8 Cl cases, the results indicate that a significant induction period would be present in Z–N systems employing such donors or having such a catalytic center, before catalysis could commence.