Synthesis of unbridged metallocene catalyst for propylene polymerization

An unbridged metallocene catalyst bis(2,4,6-trimethylindenyl)zirconium dichloride (Cat-I) was synthesized. Propylene polymerization was carried out with this catalyst and the results were compared with bis(2,4,7-trimethylindenyl)zirconium dichloride (Cat-II) to investigate the steric effects of substituents on the catalytic activity and microstructure of the resulting polymer. The differences of the methyl group position in Cat-I and Cat-II have apparent effect on the polymerization behavior. Comparable activity of the catalyst was observed at 0 and 25 °C polymerization temperature and the microstructure of the polymer was almost the same.