Synthesis of palladium complexes containing 2-methoxycarbonyl-6-iminopyridine ligand and their catalytic behaviors in reaction of ethylene and norbornene

A series of palladium complexes (C1-C7) have been prepared by the reaction of PdCl₂(CH₃CN)₂ with 2-methoxycarbonyl-6-iminopyridines, L1-L7. The 2-methoxycarbonyl-6-iminopyridines and their complexes were fully characterized by FT-IR, NMR spectra and elemental analysis. Structures of C1, C2, C4, C5 and C6, C7 were determined by X-ray crystallography, and these complexes fold slightly distorted square planar structures around palladium coordinated with two nitrogen atoms and two chlorides. These palladium complexes exhibited moderate catalytic activities for ethylene dimerization and/or polymerization in the presence of methylaluminoxane, and showed remarkable catalytic activity for norbornene polymerization. The catalytic behaviors of these complexes were highly affected by both the ligand employed and reaction conditions.