ansa-Cyclopentadienyl-Phenoxy Titanium(IV) Complexes (PHENICS): Synthesis, Characterization, and Catalytic Behavior in Olefin Polymerization

A series of ansa-cyclopentadienyl-phenoxy titanium complexes (PHENICS: phenoxy-induced complex of Sumitomo) (1a−e), [{Me2CCp(OC6H2-3-R-5-R′)}TiCl2] (1a, R = R′ = H; 1b, R = tBu, R′ = Me) and [{Me2Si(C5Me4)(OC6H2-3-R′′-5-Me)}TiCl2] (1c, R′′ = iPr; 1d, R′′ = tBu; 1e, R′′ = Adm), have been synthesized and characterized. It is noteworthy that the dihedral angles of the cyclopentadienyl and phenoxy moieties of the complexes 1b and 1d, revealed by X-ray crystal structure analysis, are 63.0° (1b) and 68.2° (1d), indicating a distortion from a mutual perpendicular arrangement, whereas the symmetrical patterns of the 1H NMR spectra indicate a dynamic behavior in solution. The PHENICS-type complexes exhibit good to excellent catalytic activities for copolymerization of ethylene and 1-hexene upon activation with AliBu3/[Ph3C][B(C6F5)4] cocatalyst. Particularly, the complexes with a bulky substituent at the ortho position of the phenoxy moiety showed excellent catalytic features (1d, 27 200 kg mol−1 h−1 at 80 °C, 600...