2-(1-(Arylimino)propyl)quinolin-8-olate half-titanocene dichlorides: Synthesis, characterization and ethylene (co-)polymerization behaviour

Abstract

A series of 2-(1-(arylimino)propyl)quinolin-8-olate half-titanocene dichlorides, Cp′TiCl₂L (Cp′ = η⁵-C₅H₅ or η⁵-C₅Me₅, L = 2-(1-(2,6-R¹-4-R²-phenylimino)propyl)quinolin-8-olate), was synthesized via the stoichiometric reaction of Cp′TiCl₃ with the corresponding potassium 2-(1-(2,6-R¹-4-R²-phenylimino)propyl)quinolin-8-olate salt. All titanium compounds were characterized by elemental analysis, ¹H NMR and ¹³C NMR spectroscopy; the molecular structures of two representative compounds were determined by single crystal X-ray diffraction. On activation with methylaluminoxane (MAO), all half-titanocene compounds showed high activity in ethylene polymerization, and furthermore, performed with good to high activities in the co-polymerization of ethylene with either 1-hexene or 1-octene affording polyethylenes with high co-monomer incorporation. Less bulky ortho-substituents (R¹) on the phenylimino groups were found to enhance the catalytic activities of their titanium compounds. In general, the titanium pro-catalysts containing η⁵-C₅Me₅ (C7–C12) exhibited higher activities than did their analogues bearing η⁵-C₅H₅ (C1–C6). Some of the resultant polyolefins were ultrahigh molecular weight polyethylene.