Ni(II) and Pd(II) complexes bearing novel chiral bis(β-ketoamino) ligand and their catalytic activity toward copolymerization of norbornene and polar norbornene derivatives

A series of novel Ni(II) and Pd(II) complexes bearing chiral bis(β-ketoamino) ligand were synthesized and characterized. The Ni(II) and Pd(II) complexes exhibited high activities for norbornene homopolymerization with only B(C6F5)3 as cocatalyst, for Ni(II) complex even up to 1.38 ×106 gpolymer/molNi·h. All the complexes had good thermal stability. Most importantly, the complexes also displayed high activities of 105 gpolymer/molmetal·h toward the copolymerization of norbornene and 5-norbornene-2-yl acetate with high molecular weights and tunable norbornene and 5-norbornene-2-yl acetate content. The copolymerization activity, molecular weight, and norbornene and 5-norbornene-2-yl acetate feed ratio of the Ni complex were higher than those of the Pd complex.