Steric and Electronic Effects of Tetradentate Nickel(II) and Palladium(II) Complexes toward the Vinyl Polymerization of Norbornene

Bulletin of the Korean chemical society

Ik-Mo Lee¹  Geun Hee Eom¹  Hyo Geun Koo¹  Jung Hwan Lee¹  Cheal Kim¹  Dong-Hwan Lee¹ 

关键词: Ni(II) and Pd(II) complexes;    N4-type tetradentate ligands;    Norbornene polymerization;    Electronic effect;    Steric effect;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

A series of Ni(II) and Pd(II) complexes bearing N4-type tetradentate ligands, [Ni(X1X2-6-Me2bpb) 1] and [Pd(X1X2-6-Me2bpb) 2]; 6-Me2bpb = N,N`-(o-phenylene)bis(6-methylpyridine-2-carboxamidate), X1 = Cl, H, or CH3, X2 = NO2, Cl, F, H, CH3, or OCH3) were designed, synthesized, and characterized to investigate electronic and steric effects of ligand on the norbornene polymerization catalysts. Using modified methylaluminoxanes as an activator, the complexes exhibited high catalytic activities for the polymerization of norbornene and the nickel complexes exhibited better catalytic activity the palladium complexes. Ni complex 1a with NO2 group on the benzene ring showed the highest catalytic activity of 4.9 × 106 g of PNBEs/molNi · h and molecular weight of 15.28 × 105 g/mol with PDI < 2.30. Complexes with electron-withdrawing groups are more thermally stable (> 100 °C), and tend to afford higher polymerization productivities than the ones having electron-donating groups. Amorphous polynorbornenes were obtained with good solubility in halogenated aromatic solvents. A vinyl addition mechanism has been proposed for the catalytic polymerization.

【 授权许可】

Unknown