Synthesis and characterization of trichlorotitanium 2-(2-pyridinyliminomethyl)phenolates and their ethylene (co-)polymerization behavior

The series of trichlorotitanium 2-(2-pyridinyliminomethyl)phenolates, [4,6-tBu₂C₆H₂O-2–CHNC₅R^1–4N]TiCl₃ (R^1–4 = H (1); R^1,3,4 = H, R² = Me (2); R^1,2,4 = H, R³ = Me (3); R^2,4 = H, R^1,3 = Me (4); R^1,3 = H, R² = CF₃, R⁴ = Cl (5)), were synthesized and characterized by elemental analysis and ¹H/¹³C NMR spectroscopy. The molecular structures of the representative complexes 2 and 4 were confirmed by single-crystal X-ray diffraction, and revealed distorted octahedral geometry at titanium. In the presence of MAO, all titanium pro-catalysts showed good activities for ethylene polymerization with good thermal stability at the optimum temperature of 50 °C. In comparison with the ethylene polymerization results, the activity observed for the co-polymerization of ethylene/1-hexene was far lower, but the polymers produced were of high molecular weight. For the co-polymerization of ethylene/1-octene, enhanced catalytic activity was observed, with 1-octene incorporation of up to 3.83 mol%.