Dissymmetric bis(indenyl) Zirconium Dichloride Complexes as Catalyst Precursors for Homogeneous Ethylene Polymerization

Six new dissymmetric bis(indenyl) zirconium dichloride complexes of the type (c9h7)[c9h6-(ch2)n-o-ar]zrcl2 (n = 3-5; ar = aryl group) bearing an unsubstituted and an ω-aryloxyalkyl substituted indenyl ligand were synthesized, characterized, activated with methylalumoxane (mao) and tested for ethylene polymerization. the activities of the catalysts depend very much on the steric bulk of the o-ar group as well as on the ch2- chain length between the aryloxy group and the indenyl ligand. the best activity (26233 kg pe/mol cat h) was obtained with catalyst precursor 4a (n = 3; ar = 2- biphenyl). obviously the biphenyl group and the limited length of the ch2-chain protect the oxygen atom very efficiently from coordination to an active site of the same or a neighboured molecule during the polymerization process.