Ethylene polymerization with catalyst systems based on supported metallocenes with varying steric hindrance

2003 ◽  
Vol 206 (1-2) ◽  
pp. 353-362 ◽  
Author(s):  
Rafael Guimarães ◽  
Fernanda C Stedile ◽  
João H.Z dos Santos
Keyword(s):  
Steric Hindrance ◽  
Ethylene Polymerization ◽  
Catalyst Systems

scholarly journals NMR and EPR trapping of the active species in the ethylene polymerization and trimerization catalyst systems

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
I.E. Soshnikov ◽  
N.V. Semikolenova ◽  
A.A. Antonov ◽  
K.P. Bryliakov ◽  
V.A. Zakharov ◽  
...  
Keyword(s):  
Epr Spectroscopy ◽  
Ethylene Polymerization ◽  
Catalyst Deactivation ◽  
Active Species ◽  
Ion Pair ◽  
Polymerization Catalysts ◽  
Ethylene Trimerization ◽  
Catalyst Systems

AbstractIn this work, previously undetected intermediates of several practically promising catalyst systems for ethylene polymerization and trimerization are discussed. In particular, the activation of ethylene polymerization catalysts (1) LNiCl2 (L = 2,4,6-trimethyl- (N-5,6,7-trihydroquinolin-8-ylidene)phenylamine) with AlEt2Cl and AlMe2Cl, (2) activation of bis(imino)pyridine vanadium(III) chloride L1VIIICl3 (L1 = 2,6-(ArN=CMe)2C5H3N, Ar = 2,6-iPr2C6H3; 2,6-Me2C6H3; 2,4,6-Me3C6H2; 3,5- F2C6H3) with AlMe3/[Ph3C]+[B(C6F5)]4¯ and MAO, and (3) selective ethylene trimerization catalyst (FI)TiCl3 (FI = phenoxyimine ligand with an additional aryl-OCH3 donor) with MAO have been assessed by NMR and EPR spectroscopy. The nature of ion-pair intermediates – the closest precursors of the propagating species – has been established, and the major catalyst deactivation pathways are discussed.

scholarly journals α-Diimine Ni-Catalyzed Ethylene Polymerizations: On the Role of Nickel(I) Intermediates

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1386
Author(s):  
Igor E. Soshnikov ◽  
Nina V. Semikolenova ◽  
Konstantin P. Bryliakov ◽  
Evgenii P. Talsi
Keyword(s):  
Ethylene Polymerization ◽  
Active Sites ◽  
Rational Design ◽  
Catalytic Properties ◽  
Broad Class ◽  
Polymerization Process ◽  
Diimine Ligands ◽  
Catalyst Systems ◽  
Monovalent Nickel

Nickel(II) complexes with bidentate N,N-α-diimine ligands constitute a broad class of promising catalysts for the synthesis of branched polyethylenes via ethylene homopolymerization. Despite extensive studies devoted to the rational design of new Ni(II) α-diimines with desired catalytic properties, the polymerization mechanism has not been fully rationalized. In contrast to the well-characterized cationic Ni(II) active sites of ethylene polymerization and their precursors, the structure and role of Ni(I) species in the polymerization process continues to be a “black box”. This perspective discusses recent advances in the understanding of the nature and role of monovalent nickel complexes formed in Ni(II) α-diimine-based ethylene polymerization catalyst systems.

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