Abstract
A number of new half‐sandwich titanium(IV) complexes of the type [Cp′TiCl~2~{N(2,6‐R^1^~2~C~6~H~3~)R^2^}] [R^1^ = i__Pr (1, 2, 4), Me (3, 5); R^2^ = Me (1, 3, 4, 5), Bn (2); Cp′ = Cp (1, 2, 3), Cp* (4, 5)] have been synthesized by the reaction of [Cp′TiCl~3~] with the lithium salts of the corresponding anilide in toluene or diethyl ether. All titanium complexes were characterized by ^1^H and ^13^C NMR spectroscopy and elemental analyses. The molecular structures of complexes 1, 4, and 5 were determined by single‐crystal X‐ray diffraction analysis. When activated with Al__i__Bu~3~ and Ph~3~CB(C~6~F~5~)~4~, complexes 1–5 exhibited reasonable catalytic activity in ethylene polymerization, producing high‐ or ultra‐high‐molecular‐weight polyethylene. It was found that complex 4 shows the highest catalytic activity in ethylene polymerization and complexes 1–3 produced ultra‐high‐molecular‐weight (M~η~__ > 3 × 10^6^ g mol^–1^, viscosity‐average molecular weight) polyethylene. The copolymerization of ethylene with 1‐hexene catalyzed by these complexes in the presence of Al__i__Bu~3~/Ph~3~CB(C~6~F~5~)~4~ was also investigated. Complexes 4 and 5 with the pentamethylcyclopentadienyl ligand were found to show higher catalytic activity in ethylene/1‐hexene copolymerization and produced poly(ethylene‐co‐1‐hexene)s with much higher molecular weights and co‐monomer incorporation than their cyclopentadienyl analogues 1–3 under similar conditions. The co‐monomer incorporation abilities of complexes 4 and 5 are relatively high in comparison with other half‐sandwich titanium catalyst systems.