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, 54, 3495–3505

A continuing legend: the Brookhart-type α-diimine nickel and palladium catalysts

“…Three-dimensional geometry Ni-and Pd-based α-diimine complexes with a bulky bridged backbone. [105][106][107][108][109][110][111] played high thermal stability, high activities of up to 3.2 × 10 6 g PE (mol Pd h) −1 (60°C, 15 min), and high polymer M n (up to 538 000) in ethylene polymerization. More interestingly, semicrystalline low-density branched (23-29/1000 C) PEs with high T m of up to 99°C were obtained.…”

“…17) containing a bulky bis(α-diimine) ligand. 109,110 These catalysts demonstrated high thermal stability and high catalytic activity toward NB polymerization. They also studied a related 6,13-dihydro-6,13-ethanopentacenebased nickel complex C34 (Fig.…”

Synthesis of bis-(benzocyclohexan-ketoimino) Ni(ii) with different electron groups and their catalytic copolymerization of norbornene and polar norbornene

“…It has been reported that PNB obtained by nickel catalysts could be dissolved in chlorobenzene at room temperature in the 2000s, and the solubility and processability of PNB have been improved. 5,7 Introducing polar groups [8][9][10][11] or exible chains 12,13 into the PNB backbone has become an effective means of solving the problem. The design and synthesis of particularly efficient and stable catalysts is very important for the polymerization.…”

Bis-(salicylaldehyde-benzhydrylimino)nickel complexes with different electron groups: crystal structure and their catalytic properties toward (co)polymerization of norbornene and 1-hexene

“…However, the further development of norbornene is hampered by its poor bond properties, low solubility and poor mechanical properties. At present, the introduction of polar groups [18][19][20] or exible chains [21][22][23][24][25] on the norbornene backbone is the most effective means to solve this problem. In order to achieve this goal, it is important to synthesize some efficient catalysts.…”

“…Norbornene is a typical cycloolen with many advantages of cycloolens, but due to the presence of bicyclic skeletons in the polymer, it is brittle and has a small elongation at break. In order to improve its defects, the copolymer obtained by copolymerizing norbornene with a-olen 22,23,36 not only can reserve the heat resistance and dimensional stability of polynorbornene, but also has excellent optical properties, good processing and solubility, which has attracted scholars's attention at both home and abroad. For example, Kaminsky group 37 achieved the copolymerization of norbornene with ethylene using a metallocene catalyst.…”