Highly symmetric single nickel catalysts bearing bulky bis(α-diimine) ligand: Synthesis, characterization, and electron-effects on copolymerization of norbornene with 1-alkene at elevated temperarure

Abstract

Three new three-dimensional geometry bulky α-diimine ligands (L) containing electron-donating and electron-withdrawing groups, 9,10-dihydro-9,10-ethanoanthracene-11,12-di(Ar)imine (Ar = p-PhCH3, L1; Ar=p-PhCl, L2; Ar=p-PhCF3, L3.), and their corresponding single Ni(II) catalysts,NiL2Br2 (Ni(L1)2Br2, Ni(L2)2Br2, and Ni(L3)2Br2, were synthesized and the molecular structure were determined by X-ray crystallography. All NiL2Br2 catalysts were tested for norbornene polymerization and copolymerization of norbornene with 1-alkene after activation with B(C6F5)3. The results that the polymerization catalytic activities for norbornene up to 105 gpolymer/molNi·h even at 140 °C, shown that NiL2Br2 catalysts have high thermal stability. Meanwhile, catalysts with electron-withdrawing groups could achieve higher reactivity. The obtained poly(NB-co-1-alkene)s were confirmed to be vinyl-addition copolymers and noncrystalline. All copolymers exhibited high 1-alkenes insertion ratio, good thermal stability (Td > 375 °C), high molecular weight (up to 105 g/mol), good solubility in common organic solvents and could be processed into films with good transparency in the visible region. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016.