A new monocyclopentadienylamido complex, [η5:η-(2,3-Me2Benz[e]Ind)SiMe2N t Bu]TiCl2 (I), was synthesized as catalyst precursor. The studies on the homopolymerization and copolymerization of 4-methyl-1-pentene (P) and ethylene (E) were presented, by comparing complex I with other CpA complexes and Cp2M zirconocenes. The complex I, activated with methylaluminoxane, provided an enhanced copolymerization activity, an excellent incorporation of 4-methyl-1-pentene into the polyethylene chain, and an increased copolymer molecular weight. Analysis of 13C NMR spectra of polymers, combined with the monomer reactivity ratios and the polymerization results, demonstrated that the regioselectivity of monomer insertion, tacticity, productivity, molecular weights, and polymer microstructure are significantly dependent on the ligand substitution pattern and the metal atom in CpA complexes. The CpA I-derived poly(4-methyl-1-pentene-co-ethylene)s contained a significant amount of regioirregular arrangement of 4-methyl-1-pentene unit, but with no virtually consecutive 4-methyl-1-pentene sequence. In contrast, the [η5:η1-(Me4C5)SiMe2N t Bu]TiCl2 (IV)-derived copolymers revealed the small clustered sequence (e.g., EPPE) but without any regioirregular arrangement of 4-methyl-1-pentene units. The copolymers prepared with [η5:η1-(Flu)SiMe2N t Bu]TiCl2 (VI) not only showed quite different microstructure from that based on catalysts I and IV but also manifested the more pronounced tendency to form an alternating distribution of monomers in the polymer chains. Furthermore, the VI-derived copolymer contained neither a regioregular insertion of comonomer nor the consecutive 4-methyl-1-pentene sequences.

As modifications of the effective catalyst precursor for syndiospecific styrene polymerization, namely [2-Me-thBenz[e]Ind]TiCl3 (Ic), [2,3-Me2-thBenz[e]Ind]TiCl3 (IIc), [1,2,3-Me3-thBenz[e]Ind]TiCl3 (IIIc), and [2-Me-3-Ph-thBenz[e]Ind]TiCl3 (IVc) have been synthesized to examine the influence of ligand pattern on the catalyst activity and polymer properties. These complexes, activated by methylaluminoxane (MAO), showed high activities compared with previously employed titanocene catalysts. Of all titanocenes examined, [2-Me-3-Ph-thBenz[e]Ind]TiCl3 (IVc)/MAO showed the highest activity and stability at an even fairly low Al/Ti ratio of 1000, revealed the excellent control over the stereoregular insertion of monomer, and exhibited a significant increase of the ratio of the propagation rates to chain transfer termination as evidenced by the kinetic results, thus producing polymers with the highest syndiotacticity and molecular weight. The kinetic investigations, combined with the EPR spectrum and polymerization experiments, showed that the higher activity of tetrahydrobenz[e]indenyl-based systems is due to a great number of active species.

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