ansa Metallocene complexes of zirconium and hafnium with –SiMe2-1,2-C6H4-CH2- bridged indenyl ligands as catalyst precursors for homogeneous ethylene polymerization

Three new ansa metallocene dichloride complexes of zirconium and hafnium with a 1- methylene-2-dimethylsilylene phenylene bridge connecting two indenyl groups either in the 1,1′ or 1,2′ positions were synthesized and characterized. These complexes were tested for homogeneous ethylene polymerization after activation with methylaluminoxane (MAO). Zirconium catalysts with 1,2′-bridged bis-indenyl ligands showed higher activities (27100 kg PE/molcat. h) than 1,1′-bridged catalysts (21700 kg PE/molcat.h). The analogous hafnium catalyst with a 1,2′-bridged bis-indenyl ligand showed a much lower performance (1500 kg PE/molcat.h).