The syntheses, structures and olefin polymerization behavior of Ti complexes containing a pair of chelating aminotropone [ON] ligands are reported. DFT studies revealed that bis(aminotropone) Ti complexes, when activated, provide a metal alkyl in the cis position to a vacant coordination site for monomer binding, suggesting great potential for the polymerization of olefinic monomers. Unlike Ti‐FI catalysts, bis(aminotropone) Ti complexes do not require the presence of steric bulk in close proximity to the anionic donor. Bis(aminotropone) Ti complexes combined with MAO display high ethylene polymerization activities (max. 27 200 kg polymer per mol catalyst and hour) comparable to those obtained with early group‐four metallocene catalysts under identical conditions.

In this article we reported synthesis, characterization and ethylene polymerization behavior of two new late transition metal 2,6-bis(imino)pyridine catalysts based on iron(II) possessing different substituents of NO 2 (catalyst b) and OMe (catalyst c) at the para position of the pyridine ring. Theoretical study exhibited more positive charge on the central metal of the catalyst b, leading to higher activity offset by lower thermal stability and life time.

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Three FI-like Zr-based catalysts, Bis[1-[(phenylimino)methyl]-2-naphtholato]zirconium(IV) dichloride (1), Bis[1-[(mesitylimino)methyl]-2-naphtholato]zirconium(IV) dichloride (2) and Bis[1-[(2,6-diisopropylphenyl)imino] methyl-2-naphtholato]zirconium(IV) dichloride (3) were prepared by changing the ligand from salicylaldehyde imine ligand, which is a well known FI catalysts, to 2-hydroxynaphthalene-1-carbaldehyde imine ligand and used for polymerization of ethylene. Triisobutylaluminum (TIBA) and methylaluminoxane (MAO) were used as scavenger and cocatalyst, respectively. Introduction of the bulky substitution phenyl ring on the N of the phenoxy imine ligand enhanced the viscosity average molecular weight of the obtained polymer strongly. Catalyst 3 produced the highest viscosity average molecular weight (M v ) of the obtained polyethylene, but showed the lowest catalytic activity. The activity of all the catalysts was increased with the increase of [Al]/[Zr] molar ratio to an optimum value followed by a slight decrease at higher [Al]/[Zr] molar ratios. Optimum activity of catalyst 1 was obtained at about 30°C while the highest activity of catalysts 2 and 3 was obtained at about 40°C following a sharp decrease at higher temperatures. The rate/time profile of the polymerization decayed with a short acceleration period for all of the catalysts. The polymerization activity was increased with increasing the hydrogen concentration due to the fast hydrogenation of sterically more hindered and less reactive intermediates such as those resulting from 2,1-insertions. It is noteworthy that the experimental results indicated that the hydrogen does not act as a chain transfer