A New Class of Pyridine-Amide Containing Ti and Zr Based Catalysts for Olefin Polymerization: Influence of Ligand Substituents

Abstract

Two tridendate pyridine-amide ligands in di-deprotonated form have been used to synthesize new titanium and zirconium complexes. The molecular structure of pentafluoro containing Titanium and Zirconium complexes were determined by DFT calculations. These new metal complexes have been further evaluated for ethylene polymerization activity in the presence of co-catalyst methylaluminoxane (MAO) under atmospheric pressure, producing polyethylenes with moderate molecular weights and unimodal molecular weight distribution. Remarkably, zirconium complexes show higher activity than titanium complexes under the same polymerization condition. The catalytic activity of all the complexes were found to be temperature dependent and reach their highest efficiency at 70 °C. The influence of the nature of the ligands and reaction parameters upon the catalytic activities has been studied. Additionally, the pentafluoro containing Zirconium and Titanium complexes were further evaluated for the copolymerization of ethylene and propylene and exhibited good catalytic activity. A new class of titanium and zirconium based metal complexes were synthesised from pyridine-amide containing ligands. The synthesised complexes have been evaluated for ethylene polymerization in the presence of co-catalyst methylaluminoxane (MAO) under atmospheric pressure. Interestingly, zirconium complexes show high catalytic activities than titanium complexes under the same polymerization condition.