Synthesis, characterization and polymerization activity of copper complexes with N, O-chelate ligands

Abstract

A series of N, O-chelate copper complexes based on Schiff base ligands are reported. Treatments of copper acetate hydrate Cu(OAc)2·H2O with ligands L1–L5 afford the mononuclear N, O-chelate complexes 1–5, respectively. These complexes have similar solid state structures, in which the metal centers are coordinated by two nitrogen atoms of imine groups and bonded to two oxygen atoms. Complexes 1–5 exhibit moderate to good catalytic activities for norbornene polymerizations in the presence of methylaluminoxane (MAO) as cocatalyst. Both the electronic effect and the steric hindrance of the substituents have influences on polymerization behaviors. Catalytic activity up to 1.9×106gPNBmol–1Cuh–1 was obtained under optimal conditions. All complexes were fully characterized by elemental analysis and IR and NMR spectroscopies. Molecular structures of 1 and 4 were further confirmed by single-crystal X-ray diffraction.