NMR spectroscopic identification of Ni(ii) species formed upon activation of (α-diimine)NiBr2 polymerization catalysts with MAO and MMAO

The ion pair [LNi^II(μ-Me)₂AlMe₂]⁺[MeMAO]⁻ is formed at the initial stage of LNiBr₂ activation with MAO, whereas [LNi^II–^tBu]⁺[MeMMAO]⁻ prevails in the LNiBr₂/MMAO system.

Ultra-high molecular weight elastomeric polyethylene using an electronically and sterically enhanced nickel catalyst

Highly active para-t-Bu-containing 1,2-bis(imino)acenaphthene-Ni(ii) catalysts are disclosed which afford hyper-branched PEs with M_w's up to 3.1 × 10⁶ g mol⁻¹; high tensile strength, excellent shape fixity as well as high elongation at break are a feature.

Reactivity of cationic α-diimine cyclopentadienyl nickel complexes towards AlEt2Cl: synthesis, characterisation and ethylene polymerisation

Cationic α-diimine cyclopentadienyl nickel complexes transform into intermediates upon reaction with AlEt₂Cl giving rise to active ethylene polymerisation catalysts.

Ethylene polymerization catalyzed by bridging Ni/Zn heterobimetallics

The effect of proximal Zn halides on Ni-catalyzed ethylene polymerization is reported in this work.

Ethylene polymerization catalyzed by dinickel complexes with a double-decker structure

Double-decker dinickel catalysts, even without any substituent on an ortho-position, afforded high molecular weight polyethylene with high crystallinity and less branching.

Highly branched unsaturated polyethylenes achievable using strained imino-cyclopenta[b]pyridyl-nickel precatalysts

Highly branched and unsaturated PEs with narrow PDIs have been obtained using nickel catalysts that display high activities, rapid regeneration of active species and high rates of chain isomerization.

Controlling the molecular weights of polyethylene waxes using the highly active precatalysts of 2-(1-aryliminoethyl)-9-arylimino-5,6,7,8-tetrahydrocycloheptapyridylcobalt chlorides: synthesis, characterization, and catalytic behavior

2-(1-aryliminoethyl)-9-arylimino-5,6,7,8-tetrahydrocycloheptapyridylcobalt chlorides polymerized ethylene in high activities, producing useful waxes.

Rigid geometry 8-arylimino-7,7-dimethyl-5,6-dihydroquinolyl nickel bromides: single-site active species towards ethylene polymerization

The rigid geometry 8-arylimino-7,7-dimethyl-5,6-dihydroquinolylnickel bromides (Ni1–Ni4), when activated with either MAO or EASC, exhibit high activities towards ethylene polymerization and produce narrowly polydispersed PE, indicative of a truly single-site active species.

Synthesis, characterization, and ethylene polymerization of 1-[2,4-bis(bis(4-fluorophenyl)methyl)naphthylimino]-2-aryliminoacenaphthylnickel bromides: influences of polymerization parameters on polyethylenes

The nickel bromides (C1–C5), upon activation with Et₂AlCl, exhibited high activities toward ethylene polymerization obtaining polyethylenes with M_w from 0.86–5.58 × 10⁵ g mol⁻¹ and narrower PDI (1.22–1.99).

A practical ethylene polymerization for vinyl-polyethylenes: synthesis, characterization and catalytic behavior of α,α′-bisimino-2,3:5,6-bis(pentamethylene)pyridyliron chlorides

A series of α,α′-bis(arylimino)-2,3:5,6-bis(pentamethylene)pyridyliron chlorides exhibits high activities toward ethylene polymerization, yielding highly linear vinyl-polyethylenes.

Thermally stable and highly active cobalt precatalysts for vinyl-polyethylenes with narrow polydispersities: integrating fused-ring and imino-carbon protection into ligand design

Finely tuned cobalt complexes, upon activation with either MAO or MMAO, exhibited high activities up to 80 °C and produced highly linear vinyl-polyethylenes.

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

The title nickel systems, incorporating fluorine content on one N-aryl group, display superior productivity.

First examples of neutral and cationic indenyl nickel(II) complexes bearing arsine or stibine ligands: highly active catalysts for the oligomerisation of styrene

New indenyl nickel(ii) complexes bearing arsine or stibine ligands synthesised by a new methodology exhibit very high catalytic activities for the oligomerisation of styrene.

Nickel(II) Complexes Bearing 4-Arylimino-1,2,3-trihydroacridines: Synthesis, Characterization, and Ethylene Oligomerization

Nickel(II) complexes have attracted much attention as a new generation of olefin catalysts since the α-diiminonickel complex was discovered as a highly efficient procatalyst for ethylene polymerization. A series of novel 4-arylimino-1,2,3-trihydroacridylnickel(II) dihalide complexes was synthesized in a one-pot reaction of 2,3-dihydroacridine-4-one and different anilines with nickel(II) chloride or nickel(II) bromide 1,2-dimethoxyethane complex. The complexes were characterized by infrared spectroscopy and elemental analysis. The molecular structures of the representative complexes 4-(2,6-diisopropylphenylimino)-1,2,3-trihydroacridylnickel(II) dichloride (C3), 4-(2,4,6-trimethylphenylimino)-1,2,3-trihydroacridylnickel dichloride(II) (C4), and 4-(2,4,6-trimethylphenylimino)-1,2,3-trihydroacridylnickel(II) dibromide (C9) were confirmed by single-crystal X-ray crystallography, revealing a distorted tetrahedral geometry around the nickel(II) of C3 and distorted trigonal bipyramidal geometry for C4 and C9. With the activation of trimethylaluminium (TMA), all nickel(II) complexes exhibited good activity for ethylene oligomerization, and oligomer products ranged from butene (C₄) to hexadecene (C₁₆).

Enhancing catalytic activity towards Heck-reaction by using 4,5,9,10-tetra(arylimino)pyrenylidenyldipalladium tetrachlorides

A series of binuclear 4,5,9,10-tetra(arylimino)pyrenylidenyldipalladium(ii) tetrachloride complexes (Pd1–Pd4) was synthesized and characterized by FT-IR and NMR spectroscopy as well as elemental analysis.

Ring-tension adjusted ethylene polymerization by aryliminocycloheptapyridyl nickel complexes

The 9-aryliminocycloheptapyridyl nickel chlorides, activated by Et₃Al₂Cl₃ or MAO, exhibited high activities toward ethylene polymerization and produced highly branched PE in narrow polydispersity.

Constrained formation of 2-(1-(arylimino)ethyl)-7-arylimino-6,6-dimethylcyclopentapyridines and their cobalt(ii) chloride complexes: synthesis, characterization and ethylene polymerization

The 2-(1-(arylimino)ethyl)-7-arylimino-6,6-dimethylcyclopentapyridylcobalt complexes were constrainedly prepared, performing polymerization with MAO but oligomerization with MMAO.

Enhancing thermo-stability to ethylene polymerization: synthesis, characterization and the catalytic behavior of 1-(2,4-dibenzhydryl-6-chlorophenylimino)-2-aryliminoacenaphthylnickel halides

The title complexes exhibited high activities up to 1.09 × 10⁷ g of PE/(mol of Ni per h) in ethylene polymerization with better thermo-stability activated with ethylaluminium sesquichloride.

Targeting polyethylene waxes: 9-(2-cycloalkylphenylimino)-5,6,7,8-tetrahydrocycloheptapyridylnickel halides and their use as catalysts for ethylene polymerization

The title complexes exhibited high activities toward ethylene polymerization, producing branched polyethylene waxes.