Effect of π-donor in unbridged metallocene catalyst for propylene polymerization

A new unbridged metallocene catalyst bis(2,4-dimethyl-7-methoxyindenyl) zirconium dichloride was synthesized and polymerization of propylene was carried out with this catalyst and the results are compared with bis(2,4,7-trimethylindenyl) zirconium dichloride. The presence of π-donor substitutent on the indenyl ring led to a decrease in catalytic activity of the catalyst as well as the resulting molecular weight of the polymer as compared to its tri-alkyl substituted congener. The methoxy group deactivates the catalyst and also suppresses the favorable effect of other methyl substituents present in the indenyl ligand.