Syntheses, Characterization, and the Ethylene (Co-)Polymerization Screening of 2-Benzimidazolyl-N-phenylquinoline-8-carboxamide Half-Titanocene Chlorides

A series of 2-benzimidazolyl-N-phenylquinoline-8-carboxamide half-titanocene chlorides, CpTiLCl (C1−C6: Cp = η5-C5H5; L = 2-(1H-benzo[d]imidazol-2-yl)-N-(2,6-R1-4-R2-phenyl)quinoline-8-carboxamide derivatives; C1: R1 = i-Pr, R2 = H; C2: R1 = Et, R2 = H; C3: R1 = Me, R2 = H; C4: R1 = Me, R2 = Me; C5: R1 = H, R2 = H; C6: R1 = F, R2 = H), have been synthesized by the stoichiometric reaction of half-titanocene trichlorides with the corresponding potassium 2-benzimidazolyl-N-phenylquinoline-8-carboxamide. All complexes are fully characterized by elemental and NMR analyses, as well as single-crystal X-ray diffraction for complexes C1, C2, and C6. In addition, the oxo-bridged dinuclear complex C7 was separated from the solution of C6 in air. These complexes, C1−C6, activated with methylaluminoxane (MAO), exhibit high catalytic activities toward both ethylene polymerization and copolymerization of ethylene with α-olefins. According to the catalytic system of C1/MAO, both elevating the reaction temperature and increasing the ratio of MAO to titanium precursor enhance the productivities; however, the molecular weights of the resultant polymers obtained decrease against their higher activities. Moreover, copolymerizations of ethylene with either 1-hexene or 1-octene effectively produce copolymers with incorporated comonomers of 2.0−5.0% mol.