2-{2,6-Bis[bis(4-fluorophenyl)methyl]-4-chlorophenylimino}-3-aryliminobutylnickel(II) bromide complexes: Synthesis, characterization, and investigation of their catalytic behavior

• 2-{2,6-Bis[di(4-fluorophenyl)methyl]-4-chlorophenylimino}-3-aryliminobutane derivatives.
• 2-{2,6-Bis[di(4-fluorophenyl)methyl]-4-chlorophenylimino}-3-aryliminobutylnickel bromide.
• Distorted-pyramidal geometry for the four-coordinate nickel complex.
• Highly active nickel precatalyst in ethylene polymerization.
• Highly branched bimodal polyethylenes.

The series of 2-{2,6-bis[di(4-fluorophenyl)methyl]-4-chlorophenylimino}-3-aryliminobutane derivatives (L1–L5) and their nickel(II) dibromide complexes (Ni1–Ni5) were synthesized, and all organic compounds were fully characterized by the Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy and by elemental analysis, while the nickel complexes were characterized by FT-IR spectroscopy, elemental analysis, as well as by single-crystal X-ray diffraction for two representative examples, namely Ni1 and Ni4. A distorted tetrahedral geometry was observed for these four-coordinate nickel complexes. Upon the activation with either Methylaluminoxane or modified methylaluminoxane as co-catalyst, all nickel complex precatalysts showed very high activity toward ethylene polymerization with activities of up to 107 g(PE)·mol−1(Ni)·h−1, and afforded highly branched polyethylene with a bimodal distribution.

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