Group (IV) Metallocene Complexes with Bulky ω-aryloxyalkyl-Substituted Indenyl Ligands as Catalyst Precursors for Homogeneous Ethylene Polymerization

A series of seven new complexes of zirconium and hafnium with bulky ω-aryloxyalkyl substituted indenyl ligands were synthesized and characterized by NMR spectroscopy and elemental analysis. These complexes were activated with methylaluminoxane and tested for homogeneous ethylene polymerization. The zirconium catalysts showed higher activities than their hafnium analogues. The effects of increasing separation between the indenyl and the aryloxy substituent and the introduction of an extra methyl group on the indenyl moiety were also investigated. Catalyst 6 bearing a spacer chain of three methylene groups between the indenyl and aryloxy substituents showed the highest activity (15500 kg PE/mol cat. h). The increase in the spacer chain length resulted in the decrease in catalyst activities.