Mechanism of Initiation in the Phillips Ethylene Polymerization Catalyst: Ethylene Activation by Cr(II) and the Structure of the Resulting Active Site

ACS Catalysis ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 7442-7455 ◽  
Author(s):  
Carole Brown ◽  
Adrian Lita ◽  
Yuchuan Tao ◽  
Nathan Peek ◽  
Mark Crosswhite ◽  
...  
Keyword(s):  
Active Site ◽  
Ethylene Polymerization ◽  
Polymerization Catalyst

Mechanism of Initiation in the Phillips Ethylene Polymerization Catalyst: Redox Processes Leading to the Active Site

ACS Catalysis ◽  
2015 ◽  
Vol 5 (9) ◽  
pp. 5574-5583 ◽  
Author(s):  
Carole Brown ◽  
J. Krzystek ◽  
Randall Achey ◽  
Adrian Lita ◽  
Riqiang Fu ◽  
...  
Keyword(s):  
Active Site ◽  
Ethylene Polymerization ◽  
Redox Processes ◽  
Polymerization Catalyst

Remote dibenzocycloheptyl substitution on a bis(arylimino)pyridyl-iron ethylene polymerization catalyst; enhanced thermal stability and unexpected effects on polymer properties

2021 ◽  
Author(s):  
Liwei Guo ◽  
Wenjuan Zhang ◽  
Furong Cao ◽  
Youshu Jiang ◽  
Randi Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ethylene Polymerization ◽  
Chloride Complexes ◽  
Polymerization Catalyst ◽  
Polymer Properties

Four examples of para-dibenzocycloheptyl-substituted 2,6-bis(arylimino)pyridyl-iron(II) chloride complexes, [2,6-{(2-R1,4-(C15H13),6-R2C6H2)N=CMe}2C5H3N]FeCl2 (R1 = R2 = Me Fe1, Et Fe2, iPr Fe3, R1 = Me, R2 = Et Fe4), have been synthesized and characterized...

scholarly journals Supersize Cp! Tetrabenzo[a,c,g,i]fluorenyl complexes of yttrium

2017 ◽  
Vol 95 (4) ◽  
pp. 363-370 ◽  
Author(s):  
Jianlong Sun ◽  
David J. Berg ◽  
Brendan Twamley
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ethylene Polymerization ◽  
Nmr Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
Trinuclear Cluster ◽  
Polymerization Catalyst ◽  
Dynamic Nuclear Magnetic Resonance ◽  
Trimethylsilyl Isocyanate

The synthesis of tetrabenzo[a,c,g,i]fluorenyl (Tbf) yttrium dialkyl complexes, (Tbf)Y(CH2SiMe3)2(L) (L = tetrahydrofuran (THF), 1; L = bipy, 2), by direct protonolysis of the tris(alkyl) complex, Y(CH2SiMe3)3(THF)2, are reported. The X-ray crystal structures of 1 and 2 display the helical twisting typically observed for the Tbf ligand. Dynamic nuclear magnetic resonance (NMR) studies on 1 show a barrier to Tbf helical inversion (epimerization or “wagging”) of 38.1 ± 0.5 kJ mol−1. The reaction of 1 with acidic hydrocarbons such as 1,3-bis(trimethylsilyl)cyclopentadiene or trimethylsilylacetylene results in protonolysis to form the mixed Cp derivative [(Tbf){C5H3(SiMe3)2}Y(CH2SiMe3)(THF)] (3) or [(Tbf)Y(CCSiMe3)2(THF)]n (4), respectively. In the case of 4, a small amount of the trinuclear cluster (Tbf)Y3(μ3-CCSiMe3)2(μ2-CCSiMe3)3(CCSiMe3)3(THF)2 (5) was isolated and characterized by X-ray crystallography. Dialkyl 1 undergoes smooth insertion of trimethylsilyl isocyanate to afford [(Tbf)Y{κ2-(N,O)-Me3SiN(Me3SiCH2)CO}2(THF)] (6) but it does not react with alkenes. Treating 1 with [Ph3C]+[B(C6F5)4]− in bromobenzene generates a moderately active ethylene polymerization catalyst (36 kg mol−1 h−1 bar−1).

IRS study of ethylene polymerization catalyst SiO2/methylaluminoxane/zirconocene

1999 ◽  
Vol 142 (1) ◽  
pp. 27-37 ◽  
Author(s):  
V.N. Panchenko ◽  
N.V. Semikolenova ◽  
I.G. Danilova ◽  
E.A. Paukshtis ◽  
V.A. Zakharov
Keyword(s):  
Ethylene Polymerization ◽  
Polymerization Catalyst
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