1‐(2,6‐dibenzhydryl‐4‐fluorophenylimino)‐2‐aryliminoacenaphthylylnickel halides highly polymerizing ethylene for the polyethylenes with high branches and molecular weights

Abstract

A series of 1-(2,6-dibenzhydryl-4-fluorophenylimino)-2-aryliminoacenaphthylene derivatives (L1-L5) and their halonickel complexes LNiX 2 (X 5 Br, Ni1-Ni5; X 5 Cl, Ni6-Ni10) are synthesized and well characterized. The molecular structures of representative complexes Ni2 and Ni4 are confirmed as the distorted tetrahedron geometry around nickel atom by the single crystal X-ray diffraction. Upon activation with methylaluminoxane, all nickel complexes show high activities up to 1.49 3 10 7 g of PE

Raising the N-aryl fluoride content in unsymmetrical diaryliminoacenaphthylenes as a route to highly active nickel(ii) catalysts in ethylene polymerization

“…The mono-ketone precursor is not commercially available and can be readily synthesized by the condensation reaction of acenaphthylene-1,2-dione with 2,6-bis(bis(4-fluorophenyl)methyl)-4-fluoro-benzenamine. [5][6][7][8] Scheme 2. Synthesis of ligands L1 -L5 and their nickel complexes Ni1 -Ni10.…”

“…In comparison with previous studies it would appear the introduction of para-fluorides to all five of the phenyl groups of the N-2,6-benzydrylphenyl unit described herein is having a positive effect on the catalytic activity. For example, for precatalysts bearing one 2,6-bis(benzhydryl)-4-fluorophenyl group (C, Scheme 1), 7 . While parafluorides can exhibit a positive electron-donating mesomeric effect (via p−π F−Ar bonding), 14 they can also display powerful inductive effects and it is this property that is viewed as responsible for the performance characteristics identified here.…”

“…From our viewpoint, these catalytic systems show considerable opportunities for potential commercialization as they address two of the major drawbacks of this type of catalyst relating to their thermostability and catalytic activity. 2 With a view to improving these parameters further we have found that the introduction of halide substituents to the N-2, 6-substituted phenyl group (C, Scheme 1) 6,7 or the aryl groups belonging to the benzhydryl substituents (D, Scheme 1), 8 has a positive effect on activity. Some justification for these results comes from computational work that points towards the electronegativity of these substituents (F or Cl) and the effect on the net charge of the active catalyst as influential.…”

Recent advances in Ni-mediated ethylene chain growth: Nimine-donor ligand effects on catalytic activity, thermal stability and oligo-/polymer structure

“…6) [63][64][65][66][67][68]. When the para-R group is Me (14a), activation with either Et2AlCl or MAO, led to an exceptionally active catalyst (up to 1.1 × 10 7 g(PE) mol -1 (Ni) h -1 ) producing highly branched polyethylene [63].…”

“…5) [60][61][62][63][64][65][66][67][68][69][70][71][72][73]. Complexes 11-13 all showed high catalytic activity and good thermal stability for ethylene polymerization [60][61][62].…”