Synthesis of Unbridged Bis(2-R-indenyl)zirconocenes Containing Functional Groups and Investigations in Propylene Polymerization

Abstract

Five new indenyl zirconium metallocenes with 2-alkyl and 2-aryl substituents were synthesized and characterized. For the synthesis of the ligand the di-Grignard reagent 1,2-bis(magnesiomethyl)benzene dichloride was explored as a synthon to 2-substituted indenes. This procedure provides access to a variety of functionalized 2-indenylmetallocenes such as bis(2-ferrocenylindene)zirconium dichloride and bis(2-adamantylindenyl)zirconium dichloride. Crystallographic characterization of bis[2-(4-(dimethylamino)phenyl)indenyl] zirconium dichloride revealed an anti conformation with a coplanar orientation of the dimethylamino substituent to the aryl ring in the solid state. The polymerization behavior of all five zirconocene dichlorides in liquid propylene was studied in the presence of MAO at various temperatures, and the results were compared to those for the known catalyst system bis(2-phenylindenyl)zirconium dichloride/MAO (M1/MAO). The productivity of the 2-arylindene metallocenes in propylene polymerization was on the order of 100−7000 kg of PP/((mol of Zr) h). In contrast, the (2-adamantylindenyl)metallocenes exhibited very low productivities of 6 kg PP/((mol of Zr) h) in propylene polymerization.