"Steric Control of Olefin Polymerization by Late Transition Metals.

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Minisymposium "Stoichiometric and Catalytic
Activation of Small Molecules by Redox Active
Metal Complexes"
Montag und Dienstag, den 14. und 15.01.02, 14.00
Uhr, Hörsaal H3 der Chemischen Institute
Organizer Prof. Dr. Dr. h.c. Rudi van Eldik
"Steric Control of Olefin Polymerization by Late
Transition Metals. A Theoretical Study Based on
a Combined Quantum Mechanical and Molecular
Mechanical Approach."
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Reaction free energies
make use of intrinsic reaction coordinate
(IRC) dynamics with constraint for points on
IRC free energy change obtained by
integration of the force on constraint
(thermodynamic integration)
TS
min.
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Olefin Polymerization
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Successful Single Site Catalysts
Brinzinger/Kaminsky
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Elementary Steps in Polymerization
Propagation by insertion
p-complex
Termination by b-Hydrogen Transfer
Kinetics
Olefin concentration
Initial catalyst conc.
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Elementary Steps in Polymerization
Propagation by insertion
p-complex
Termination by b-Hydrogen Transfer
Rotation
Branching
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Fe
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Elementary Steps in Polymerization
Propagation by insertion
p-complex
Termination by b-Hydrogen Transfer
Rotation
Branching
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Liqun Deng, Tom Ziegler, Tom K. Woo, Peter Margl
and Liangyou Fan, ", Organometallics, 17 (1998)
3240-3253.
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Liqun Deng, Tom Ziegler, Tom K. Woo, Peter
Margl and Liangyou Fan, Organometallics, 17
(1998) 3240-3253.
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16.0 2.3 8.7 2x108 15.3
3.6 6.9 3x107
Liqun Deng, Tom Ziegler, Tom K. Woo, Peter
Margl and Liangyou Fan, Organometallics, 17
(1998) 3240-3253.
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Brookhart Polymerization Catalyst
CEN Feb. 5, 1996
Polymer Catalyst System Dupont Eyes New
Polyolefin Business
Brookhart catalyst
highly linear to moderately branched

• temperature Temp ? branching ?
• monomer pressure Et ? branching ?
• bulk of substituents bulk ? branching ? MW ?

• high MWs
• good activities

Johnson, L. K. Killian, C. M. Brookhart, M. J.
Am. Chem. Soc. 1995, 117, 2343.
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L. Deng, P. M. Margl and T. Ziegler, Jacs 1997,
119, 1094-1100.
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L. Deng, T. K. Woo, L. Cavallo, P. Margl and T.
Ziegler, Jacs 1997, 119, 6177-6186.
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L. Deng, T. K. Woo, L. Cavallo, P. Margl and T.
Ziegler, Jacs 1997, 119, 6177-6186.
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Experiment M. Brookhart, Jacs 1999 121
10634
Theory L. Deng, Jacs 1997, 119, 6177-6186.
Insertion Barrier Exp 13.5 kcal/mol QMMM 12
kcal/mol
Exp 13.5 kcal/mol
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Elementary Steps in Polymerization
Propagation by insertion
p-complex
Termination by b-Hydrogen Transfer
Rotation
Branching
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Isotactic and Syndiotactic Polymerization
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Branching of Polyolefins
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Branching in Pd(II) catalyzed propylene
polymerization
Pd(II)- Brookhart Catalyst
Artur Michalak and Tom Ziegler Organometallics
18 (1999) 3998-4004
Artur Michalak and Tom Ziegler Organometallics,
2000, 1850-1858
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Experimentalists Explanation of Branching

• Explanation from experimentalists
• 1,2 insertion preferred over 2,1 insertion
• 2,1 insertion product isomerizes (insertion hard)

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Full picture of polymerization/isomerization
Artur Michalak and Tom Ziegler Organometallics,
2000, 1850-1858
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Elimentary reactions and modeling
Artur Michalak and Tom Ziegler Organometallics,
2000, 1850-1858
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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Models for the catalyst
1) generic system R H Ar H

• 2) a variety of systems with
• different substituents
• R H Ar Ph
• R H Ar Ph (Me)2
• R H Ar Ph (i-Pr)2
• R Me Ar H
• R Me Ar Ph (Me)2
• R Me Ar Ph (i-Pr)2
• R2 An Ar H
• R2 An Ar Ph (i-Pr)2

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Artur Michalak and Tom Ziegler Organometallics,
2000, 1850-1858
Branching and Steric Bulk
ArH RH
3331000 branch ratio 2,1 preferred over
1,2 Insertion faster than isomerization
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Branching and Steric Bulk
Ar Ar RH
1221000 branch ratio 2,1 preferred over
1,2 isomerization faster than insertion
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Branching and Steric Bulk
Ar Ph (i-Pr)2 RMe
2501000 branch ratio 1,2 preferred over 2,1 2,1
product isomerizes (insertion hard)
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Graduate Students
Fan Liangyou
Liqun Deng
Tom Woo
Eva Zurek
Kumar Vanka
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Postdoctoral Fellows
John Lohrenz
Peter Margl
Cory Pye
Rochus Schmid
C.Zhu
Mary Chan
Artur Michalak
Tim Firman
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