Nickel(II) complexes bearing the bis(β-ketoamino) ligand for the copolymerization of norbornene with a higher 1-alkene

摘要

A novel bis(β-ketoamino)Ni(II) complex catalyst, Ni{CF _3C(O)CHC[N(naphthyl)]CH _3} _2, was synthesized, and the structure was solved by a single-crystal X-ray refraction technique. The copolymerization of norbornene with higher 1-alkene was carried out in toluene with catalytic systems based on nickel(II) complexes, Ni{RC(O)CHC[N(naphthyl)] CH _3} _2(R=CH _3, CF _3) and B(C _6F _5) _3, and high activity was exhibited by both catalytic systems. The effects of the catalyst structure and comonomer feed content on the polymerization activity and the incorporation rates were investigated. The reactivity ratios were determined to be r _(1-octene) = 0.009 and r _(norbornene) = 13.461 by the Kelen-Tüd?s method for the Ni{CH _3C(O)CHC[N(naphthyl)]CH _3} _2/ B(C _6F _5) _3 system. The achieved copolymers were confirmed to be vinyl-addition copolymers through the analysis of ~1H-NMR and ~(13)C-NMR. The thermogravimetric analysis results showed that the copolymers exhibited good thermal stability (decomposition temperature, T _(dec) > 400°C), and the glass-transition temperature of the copolymers were observed between 215 and 275°C. The copolymers were confirmed to be noncrystalline by wide-angle X-ray diffraction analysis and showed good solubility in common organic solvents.