1,2-Azaborolyl-Ligated Titanium(IV) Half-Metallocenes: Synthesis, Characterization, and Catalytic Activity in Ethylene Polymerization

The synthesis and characterization of 1,2-azaborolyl (Ab)-ligated titanium­(IV) half-metallocene complexes are presented, and their catalytic properties in ethylene polymerization have been evaluated. Mono-Ab TiCl₃ complexes 3 and 4 can be conveniently converted to other half-metallocene derivatives (5–8) in moderate to good yields. The molecular structures of titanium complexes 3–8 have been determined by X-ray diffraction analysis. Upon activation with methylaluminoxanes (MAO), mono-Ab Ti half-metallocenes demonstrated high catalytic activity in ethylene polymerization (1.50 × 10⁷ g of PE (mol of Ti)⁻¹ h^–1) at a low [MAO] (Al:Ti = 30) .