Polyethylenimines: Multidentate Electron Donors for Ziegler–Natta Catalysts

Polyethylenimines, polymers bearing amino functionalities, are studied for the first time as internal electron donors for Ziegler–Natta catalysts. An advantage of polyethylenimines (PEIs) compared to the conventional phthalate electron donors is their relative harmlessness. Interaction of PEI with MgCl2 support was studied using computational (DFT; M06-2X) and experimental (PXRD, DRIFT, CP/MAS 13C NMR) methods. Quantum chemical calculations suggest that the structural variations in PEIs significantly affect their ability to stabilize the catalytically relevant MgCl2 surfaces. Coordination on the (104) surface seems to be favored upon consideration of the layered structure of MgCl2. The surface stabilization energies of branched PEIs are of the same magnitude with a phthalate electron donor reference. Experimental results indicate, in agreement with theoretical results, a strong coordination ability of branched PEI through nitrogen atoms to MgCl2. Based on spectroscopic data, nitrogen atoms of primary, sec...