2,6-Dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-chloro-aniline nickel dihalides: Synthesis, characterization and ethylene polymerization for polyethylenes with high molecular weights

A series of 2,6-dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-chloroanilines (L1–L5) and their nickel halide complexes LNiX2 (X = Br, C1–C5; X = Cl, C6–C10) were synthesized. All organic compounds were characterized by FT-IR and NMR spectroscopy and elemental analysis. The nickel complexes were characterized by FT-IR spectroscopy, elemental analysis and their structures were determined by single-crystal X-ray diffraction. Upon activation with MAO, all of these nickel complexes showed high activities (up to 107 g of PE (mol of Ni)−1 h−1) for ethylene polymerization. The resulting polyethylenes possess high molecular weights (Mw up to 106 g mol−1) and feature high degrees of branching. The MM-QEq method was employed to assess the ligands' effects on catalytic activities. The results show that higher net charges on the nickel core correlate directly with higher measured activities.

Graphical abstractThe nickel halide complexes bearing 2,6-dibenzhydryl-N-(2-phenylimino-acenaphthylenylidene)-4-chloroanilines, upon activation with MAO, showed high activities (up to 107 g of PE (mol of Ni)−1 h−1) for ethylene polymerization and produced polyethylenes with high molecular weights (Mw up to 106 g mol−1) and high branches.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Finely tuning ligands bearing bulky benzhydryl-substituent. ► Synthesis and characterization of new bidentate nickel complexes. ► Highly activity for ethylene polymerization. ► Polyethylenes with high molecular weights and high branches. ► The MM-QEq method illustrating ligands' effects on catalytic activities.