Abstract: A new Br-substituted α-diimine ligand and its corresponding Ni(II) complex, {bis[N,N′-(4-bromo-2, 6-dimethylphenyl)imino] acenaphthene}dibromonicke (2) were successfully synthesized and characterized by ¹H and ¹³C nuclear magnetic resonance, elemental analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The catalytic system, complex 2/diethylaluminium chloride (DEAC) showed higher activity for ethylene polymerization. The highest activity (3.73 × 10⁷ g/(mol.h.MPa)) was obtained with the Al/Ni molar ratio of 600 at 25 ºC. The catalyst containing electron-withdrawing group Br showed better thermodynamic stability and almost the same catalytic activity compared with the Br-free catalyst. Branching degree was increased in the presence of electron-withdrawing group Br.

Key words: α-diimine, nickel, complex, late-transition metal catalyst, diethyllaluminium chloride, ethylene, polymerization, polyethylene