Theoretical ab initio methods have been used to study the interaction between the TiCl4 catalyst and the MgCl2 support in the Ziegler-Natta catalysis. Determination of the coordination geometry between the catalyst and the support was carried out by optimizing the structure of the TiCl4MgCl2 complex. The optimized structure of the complex resembles the chain-like structure of β-TiCl3. The applicability of this model was tested by determining the most favourable place for a methyl group in the coordination sphere of the catalyst. Based on these investigations we found the catalyst complex to be octahedrally coordinated with one vacant coordination site. The effect of the support on the coordination geometry of the catalyst was also studied by enlarging the support model. The results indicate that the coordination geometry is only slightly dependent on the coordination of the magnesium atom.
Puhakka, E., Pakkanen, T., & Pakkanen, T. (1995). Theoretical investigations on Ziegler-Natta catalysis: models for the interactions of the TiCl4 catalyst and the MgCl2 support. Surface Science, 334(1-3), 289-294. https://doi.org/10.1016/0039-6028(95)00500-5