Phenylene-Bridged Cp/Carboxamide Ligands for Titanium Complexes of Various Binding Modes and Their Ethylene/1-Octene Copolymerization

o-Phenylene-bridged or substituted o-phenylene-bridged di- or trimethylcyclopentadienyl/carboxamide
ligands 2-(RMe2C5H2)-4,6-R‘2C6H2NHC(O)tBu (R = Me or H; R‘ = Me, H, or F) are prepared. When
R‘ is methyl or H, unbridged trichlorotitanium complexes containing a chloroimine unit as a pendant
group, 2-[(η5-RMe2C5H)TiCl3]-4,6-R‘2C6H2NC(Cl)tBu (7, R = H, R‘ = H; 8, R = Me, R‘ = H; 9, R
= H, R‘ = Me; 10, R = Me, R‘ = Me), are unexpectedly afforded through the successive addition of
Ti(NMe2)4 and SiCl4 to the ligands. The same treatment to the ligands where R‘ = F affords oxygen-coordinated bridged complexes [2-(η5-RMe2C5H)-4,6-F2C6H2NC(O)tBu-κO]TiCl2 (11, R = H; 12, R
= Me). The desired nitrogen-coordinated bridged complexes [2-(η5-RMe2C5H)C6H4NC(O)tBu-κ2N,O]TiMe2 (13, R = H; 14, R = Me) are obtained by reacting the corresponding dilithium compound with
Me2TiCl2. The binding modes of 7, 8, 9, 11, and 14 are confirmed by X-ray crystallography.
Trichlorotitanium complex 8 shows high activity in ethylene/1-octene copolymerization (activity, 100 ×
106 g/molTi·h at 13 bar ethylene). Trimethylcyclopentadienyl complexes show higher activity than the
dimethylcyclopentadienyl analogues, and the activities of 12 and 14 reach ∼65 × 106g/molTi·h. Complex
12 is excellent in incorporating 1-octene.