Summary Brookhart catalysts are widely used in ethylene polymerization to produce polymers with high molecular weight and crystallinity degree. In the present work, the performance of a bis(imine)pyridine iron catalyst and methylaluminoxane (MAO) as a catalytic system was evaluated for ethylene/norbornene copolymerization and the influence of adding zinc diethyl (DEZ) in the reaction medium was investigated. The results showed that the system was effective in copolymerization besides the low incorporation of norbornene in polymer chain, as indicated by multimodal profiles in DSC and high crystalline degree.

Abstract. Three-component catalytic systems based on 2,6-bis(imino) pyridine iron(II) chloride were synthesized from different ligands, which provided new alternative catalysts for polymerization of ethylene. The synthesized catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), and the lack of absorption bands was observed in the region related to the carbonyl, as well as the presence of bands in the region of imino groups corresponding to C=N bonds. Coordination with Fe was also carried out. The structure of the ligands and the new catalysts were confirmed by the elemental analysis (CHN), and 1 H-and 13 C-nuclear magnetic resonance spectroscopy. In ethylene polymerization with methylaluminoxane as a cocatalyst, the activity of catalyst C1 was high. Although this catalyst structure contains sterically bulky ligands, the metal center was not sufficiently protected allowing transfer reactions, producing polyethylene with a low molar mass and melting temperature.

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