Marked Counteranion Effects on Single-Site Olefin Polymerization Processes. Correlations of Ion Pair Structure and Dynamics with Polymerization Activity, Chain Transfer, and Syndioselectivity

2004 ◽  
Vol 126 (14) ◽  
pp. 4605-4625 ◽  
Author(s):  
Ming-Chou Chen ◽  
John A. S. Roberts ◽  
Tobin J. Marks
Keyword(s):  
Chain Transfer ◽  
Olefin Polymerization ◽  
Ion Pair ◽  
Single Site ◽  
Structure And Dynamics ◽  
Activity Chain

scholarly journals Preparation of Half- and Post-Metallocene Hafnium Complexes with Tetrahydroquinoline and Tetrahydrophenanthroline Frameworks for Olefin Polymerization

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1093 ◽  
Author(s):  
Jun Won Baek ◽  
Su Jin Kwon ◽  
Hyun Ju Lee ◽  
Tae Jin Kim ◽  
Ji Yeon Ryu ◽  
...  
Keyword(s):  
Chain Transfer ◽  
Olefin Polymerization ◽  
Ion Pair ◽  
Metallocene Catalysts ◽  
Active Complex ◽  
Ethylene Propylene ◽  
X Ray ◽  
X Ray Crystallography ◽  
Chain Transfer Polymerization ◽  
Metallocene Complexes

Hafnium complexes have drawn attention for their application as post-metallocene catalysts with unique performance in olefin polymerization. In this work, a series of half-metallocene HfMe2 complexes, bearing a tetrahydroquinoline framework, as well as a series of [Namido,N,Caryl]HfMe2-type post-metallocene complexes, bearing a tetrahydrophenanthroline framework, were prepared; the structures of the prepared Hf complexes were unambiguously confirmed by X-ray crystallography. When the prepared complexes were reacted with anhydrous [(C18H37)2N(H)Me]+[B(C6F5)4]−, desired ion-pair complexes, in which (C18H37)2NMe coordinated to the Hf center, were cleanly afforded. The activated complexes generated from the half-metallocene complexes were inactive for the copolymerization of ethylene/propylene, while those generated from post-metallocene complexes were active. Complex bearing bulky isopropyl substituents (12) exhibited the highest activity. However, the activity was approximately half that of the prototype pyridylamido-Hf Dow catalyst. The comonomer incorporation capability was also inferior to that of the pyridylamido-Hf Dow catalyst. However, 12 performed well in the coordinative chain transfer polymerization performed in the presence of (octyl)2Zn, converting all the fed (octyl)2Zn to (polyolefinyl)2Zn with controlled lengths of the polyolefinyl chain.

Silanolytic Chain Transfer in Olefin Polymerization with Supported Single-Site Ziegler−Natta Catalysts

2001 ◽  
Vol 34 (14) ◽  
pp. 4676-4679 ◽  
Author(s):  
Haruyuki Makio ◽  
Kwangmo Koo ◽  
Tobin J. Marks
Keyword(s):  
Chain Transfer ◽  
Olefin Polymerization ◽  
Single Site ◽  
Ziegler Natta Catalysts

Single-Site Heterogeneous Catalysts for Olefin Polymerization Enabled by Cation Exchange in a Metal-Organic Framework

2016 ◽  
Vol 138 (32) ◽  
pp. 10232-10237 ◽  
Author(s):  
Robert J. Comito ◽  
Keith J. Fritzsching ◽  
Benjamin J. Sundell ◽  
Klaus Schmidt-Rohr ◽  
Mircea Dincă
Keyword(s):  
Cation Exchange ◽  
Heterogeneous Catalysts ◽  
Olefin Polymerization ◽  
Metal Organic Framework ◽  
Single Site ◽  
Metal Organic ◽  
Organic Framework

scholarly journals Structure and dynamics of catalytically competent but labile paramagnetic metal-hydrides: the Ti(iii)-H in homogeneous olefin polymerization

2020 ◽  
Vol 11 (46) ◽  
pp. 12436-12445
Author(s):  
Enrico Salvadori ◽  
Mario Chiesa ◽  
Antonio Buonerba ◽  
Alfonso Grassi
Keyword(s):  
Epr Spectroscopy ◽  
Olefin Polymerization ◽  
Metal Hydrides ◽  
Open Shell ◽  
Geometrical Structures ◽  
Structure And Dynamics ◽  
Paramagnetic Metal

Catalytically competent titanium-hydrides are reactive and difficult to isolate. We use EPR spectroscopy to define the electronic and geometrical structures as well as dynamics of an open-shell Ti-H active in syndiospecific olefin polymerization.

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