Molecular-level insights into adsorption of a novel silyl ester donor on essential MgCl2 facets of supported Ziegler–Natta catalysts

Abstract This article deals with the adsorption properties of a new silyl ester donor called bis(benzoyloxy)dimethylsilane (BDMS) on the MgCl2 support of the Ziegler–Natta catalysts in both conventional and zip modes of coordination. The results confirmed the strong (by up to 47.6 kcal/mol at PBEh/TZVP) preference of BDMS for bridging over chelating or monodentate binding modes on both tetracoordinate and pentacoordinate Mg atoms. Among the spontaneous events, the lowest but appreciable preference was predicted for monodentate chemisorption on penta-coordinated Mg. The zero-point energy (ZPE) values confirmed that BDMS could be adsorbed more strongly, by 7.0 kcal/mol, on the (110) facet than on the (104) surface of the MgCl2 matrix. The enthalpy changes confirmed the ability of BDMS to effectively stabilize the lateral crystallite terminations. The observed characteristics were explained in terms of the quantum theory of atoms in molecules, natural bond orbital population, reduced density gradient, non-covalent interactions, and charge density difference. While some in-plane redistribution of charges was demonstrated, the electron transfer did not exceed 0.1 e. Overall, BDMS was shown to be more selective than the commonly used phthalate donors.