Neutral Nickel Catalysts for Olefin Homo- and Copolymerization: Relationships between Catalyst Structures and Catalytic Properties

A highly active chiral (S,S)-bis(oxazoline) Pd(ii) alkyl complex/activator catalytic system for vinyl polymerization of norbornene in air and water

The air/water-tolerant chiral Pd alkyl complexes/borate systems promote the norbornene polymerization both in air and water using unpretreated technical grade solvent and monomer with extremely high activity up to 1.7 × 10⁹ g PNB per mol_Pd per h.

Phosphine-sulfonate-based nickel catalysts: ethylene polymerization and copolymerization with polar-functionalized norbornenes

A series of biaryl-based phosphine-sulfonate nickel catalysts are shown to mediate efficient ethylene polymerization and copolymerization with polar-functionalized norbornene comonomers.

(Co-)polymerization of methylacrylate with NBE/1-hexene by (8-arylimino-5,6,7-trihydroquinolyl)(methyl)palladium chlorides: an approaching mechanism and the polymeric microstructures

The title complexes exhibited a good polymerization performance for MA monomer homopolymerization and copolymerization with either norbornene or 1-hexene as a non-polar monomer affording good co-monomer insertion.

Synthesis of hyperbranched low molecular weight polyethylene oils by an iminopyridine nickel(ii) catalyst

A 6-(2,6-dimethylphenyl)-2-(2,6-diisopropylphenyl)iminopyridine dibromo nickel(ii) complex was synthesized, characterized by X-ray diffraction analysis and tested in ethylene polymerization using diethylaluminumchloride as the cocatalyst.

Glyoxalbis(2-methylmercaptoanil) complexes of nickel and ruthenium: radical versus non-radical states

The molecular and electronic structures of nickel(ii) and ruthenium(ii) complexes of glyoxalbis(2-methylmercaptoanil) and their reduced and oxidized analogues are reported.

A RAFT/MADIX method finely regulating the copolymerization of ethylene and polar vinyl monomers under mild conditions

A RAFT/MADIX method can not only copolymerize ethylene with a diverse range of functionally polar monomers, but can also easily tune the polar composition and the polar monomer distribution along the produced copolymer chains.

Unsymmetrical N-Aryl-1-(pyridin-2-yl)methanimine Ligands in Organonickel(II) Complexes: More Than a Blend of 2,2'-Bipyridine and N,N-Diaryl-α-diimines?

The new organonickel complexes [(R-PyMA)Ni(Mes)X] [R-PyMA = N-aryl-1-(pyridin-2-yl)methanimine; aryl = phenyl, 2,6-Me₂-, 3,5-Me₂-, 2,4,6-Me₃-, 2,6-ⁱPr₂-, 3,5-(OMe)₂-, 2-NO₂-4-Me-, 4-NO₂-, 2-CF₃-, and 2-CF₃-6-F-phenyl; Mes = 2,4,6-trimethylphenyl; X = F, Cl, Br, or I] were obtained as approximate 1/1 cis and trans isomeric mixtures or pure cis isomers depending on the PyMA ligand and X. The [(R-PyMA)Ni(Mes)X] complexes with X = Br or Cl were directly synthesized from the precursors trans-[(PPh₃)₂Ni(Mes)X], while [(PyMA)Ni(Mes)X] derivatives with X = F or I were obtained from [(PyMA)Ni(Mes)Br] through X exchange reactions. Although density functional theory (DFT) calculations show a preference for the sterically favored cis isomers, both isomers could be observed in many cases; in three cases, even single crystals for X-ray diffraction could be obtained for the trans isomers. Possible intermediates for the isomerization were investigated by DFT calculations. All complexes were studied by multiple spectroscopic means, electrochemistry, and spectroelectrochemistry (for the reduction processes). The long-wavelength metal-to-ligand charge-transfer (MLCT) absorptions vary markedly with the R substituent of the ligand and the cathodic electrochemical potentials to a far smaller degree. Both are almost invariable upon variation of X. All of this is in line with Ni-based and π*-based lowest unoccupied molecular orbitals (LUMOs). In line with the unsymmetric character of the N_Py^N_methanimine ligand, electrochemistry and MLCT transitions seem to not correspond to the same type of π* LUMO, making these PyMA ligands more interesting than the symmetric heteroaromatic polypyridine ligands such as 2,2'-bipyridine (bpy; N_Py^N_Py) and N,N-diaryl-substituted aliphatic α-diimines (N_methanimine^N_methanimine) such as the diaza-1,3-butadienes (DAB). First attempts to use these complexes in Negishi-type cross-coupling reactions were successful.

Nickel(ii) complexes chelated by 2,6-pyridinedicarboxamide: syntheses, characterization, and ethylene oligomerization

Ni(ii) complexes chelated by a neutral tridentate amide ligand are conveniently prepared and are highly active for ethylene oligomerization.

Influence of ligand second coordination sphere effects on the olefin (co)polymerization properties of α-diimine Pd(ii) catalysts

A series of α-diimine ligands and their corresponding palladium complexes were synthesized and characterized.