Experimental and Computational Approaches on the Isospecific Role of Monoester‐Type Internal Electron Donor for TiCl 4 /MgCl 2 Ziegler‐Natta Catalysts

In this work, a combination of experimental and computational approaches on the isospecific role of monoester‐type internal electron donors (ED) such as phenylpropionate (PhP), ethylheptanoate (EH), methylbenzoate (MB), ethylbenzoate (EB) for TiCl 4 /ED/MgCl 2 Ziegler‐Natta catalysts had been performed. The propylene polymerization results revealed that the isospecificity of catalysts increases in the following order: PhP < EH < MB < EB. The subsequent molecular modeling on the electronic properties of the donors and two kinds of cluster model catalysts: TiCl 4 /ED/MgCl 2 and TiCl 4 /ED/(MgCl 2 ) 4 based on density functional theory (DFT) method was carried out. Two kinds of ED coordination on MgCl 2 clusters through either O or O within the monoester‐type ED had been disclosed. A perfect correlation between the dipole moment of ED, the coordination bond length of O … Mg, the competitive coordination from O with Mg ion and the isospecificity of the catalysts had been established.