Syntheses, structures and catalytic activity of copper(II) complexes bearing N,O-chelate ligands

Copper complexes [Cu(Ln)2] 1–4 bearing N,O-chelating β-ketoamine ligands Ln based on condensation products of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone with aniline (L1), α-naphthylamine (L2), o-methylaniline (L3), and p-nitroaniline (L4), respectively, were synthesized and characterized by IR, 1H NMR and X-ray crystallography (except 2). They were shown to catalyze the vinyl polymerization of norbornene when activated by methylaluminoxane (MAO). Both steric and electronic effects are important and influential factors contributing to the catalytic activity of the complexes with the order of 2 > 4 > 3 > 1.

Graphical abstractCopper complexes 1–4-bearing N,O-chelating β-ketoamine ligands based on 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone condensed with aniline, α-naphthylamine, o-methylanline, and p-nitroaniline, respectively, were prepared and characterized. They were shown to catalyze the vinyl polymerization of norbornene with order of activity 2 > 4 > 3 > 1. Both steric and electronic effects of the R group are important for the catalytic activityFigure optionsDownload full-size imageDownload as PowerPoint slide