theoretical studies on the polymerization and copolymerization processes catalyzed by the late...

Theoretical studies on the polymerization

and copolymerization processes catalyzed by

the late transition metal complexes

Theoretical studies on the polymerization

and copolymerization processes catalyzed by

the late transition metal complexes

Artur Michalaka,b and Tom Zieglera

aDepartment of Chemistry,

University of Calgary,

Calgary, Alberta, Canada

bDepartment of Theoretical Chemistry

Jagiellonian University

Cracow, Poland

Artur Michalaka,b and Tom Zieglera

aDepartment of Chemistry,

University of Calgary,

Calgary, Alberta, Canada

bDepartment of Theoretical Chemistry

Jagiellonian University

Cracow, Poland

April 3, 2002April 3, 2002

OutlineOutline

• Influence of catalyst and reaction conditions on the polymer microstructure – DFT calculations and stochastic simulations• Copolymerization of -olefin with methyl acrylate – comparison of Ni- and Pd-based diimine catalysts

• Influence of catalyst and reaction conditions on the polymer microstructure – DFT calculations and stochastic simulations• Copolymerization of -olefin with methyl acrylate – comparison of Ni- and Pd-based diimine catalysts

OutlineOutline

• Influence of catalyst and reaction conditions on the polymer microstructure – DFT calculations and stochastic simulations• Copolymerization of -olefins with methyl acrylate – comparison of Ni- and Pd-based diimine catalysts

• Influence of catalyst and reaction conditions on the polymer microstructure – DFT calculations and stochastic simulations• Copolymerization of -olefins with methyl acrylate – comparison of Ni- and Pd-based diimine catalysts

Ethylene polymerization mechanismEthylene polymerization mechanism

-agostic

-complex

+ ethylene

-agostic

-agosticinsertion

Chain isomerization

-olefin polymerization mechanism-olefin polymerization mechanism

Diimine catalystsDiimine catalysts

n

Propylene:

n

Etylene:

333 methyl branches / 1000 C atoms

Linear chain

Observed: up to 130 branches / 1000 C

Observed: 210 - 333 branches / 1000 C

n

Propylene:

n

Propylene:

n

Etylene:

n

Etylene:


Linear chain



CCC

CC

CC

C

C

CC

C

CC

C

CC

C

C

CC

C

N CNC CC

C

C

CCC C

CC

Pd

CC


Influence of olefin pressure on the polymer structurehigh p - linear structureslow p - hyperbranched structures

Pd – No. of branches independent of pNi – No. of braches influenced by p

n

Propylene:

n

Etylene:


Linear chain



n

Propylene:

n

Propylene:

n

Etylene:

n

Etylene:


Linear chain



-olefin polymerization mechanism-olefin polymerization mechanism

Models for the catalyst:Models for the catalyst:

1) generic system: R = H; Ar = H1) 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


• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

CC

CCCC

CNN CCC

CCC C

Pd




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

C

CC

C

CCCC

CNN CCC

CCC C

C

Pd

C




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

CC

C

CC

C

CC

C

CC

C

C

CNN CCC

CC

C

C C

CC

Pd

CC




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

CC

CC

NN

Pd




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

CC

C

CC

C

CCCC

CNN CCC

CCC C

C

Pd

C




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

C

CC

C

C

CC

C

CC

C

CC

C

C

N CNC CC

CC

C

C C

CC

Pd

CC




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

CC

CC

C

CC

C

CC

CC

NN

Pd




• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2





• R = H; Ar = Ph• R = H; Ar = Ph (Me)2

• R = H; Ar = Ph (i-Pr)2




CC

NN

Pd

R R

Ar Ar

+

CC

NN

Pd

R R

Ar Ar

+

CCC

CC

CC

C

C

CC

C

CC

C

CC

C

C

CC

C

N CNC CC

C

C

CCC C

CC

Pd

CC

DFT calculations:DFT calculations:

A. Michalak, T. Ziegler, "Pd-catalyzed Polymerization of Propene - DFT Model Studies", Organometallics, 18, 1999, 3998-4004.

A. Michalak, T. Ziegler, "DFT studies on substituent effects in Pd-catalyzed olefin polymerization", Organometallics, 19, 2000, 1850-1858.

Examples of results:

Ethylene insertion barrier:DFT: 16.7 kcal/molexp.: 17.4 kcal/mol

Isomerization barrier:DFT: 5.8-6.8 kcal/molexp: 7.2 kcal/mol

C

CC

C

C

CC

C

CC

C

CC

C

C

N CNC CC

CC

C

C C

CC

Pd

CC

Substituent effect in real systemsSubstituent effect in real systems

Electronic preference Steric effect(generic system) (real systems)

alkyl complexes iso-propyl iso-propyl

olefin -complexes iso-propyl alkyl n-propyl alkyl

olefin -complexes propene ethene

propene insertion 2,1- 1,2-

Electronic preference Steric effect(generic system) (real systems)

alkyl complexes iso-propyl iso-propyl

olefin -complexes iso-propyl alkyl n-propyl alkyl

olefin -complexes propene ethene

propene insertion 2,1- 1,2-

Isomerization reactionsIsomerization reactions

0.000.00

+4.56+4.56

-3.42-3.42

0.000.00+5.84+5.84

+1.59+1.59

following1,2-insertion

following2,1-insertion

1 C atom attached to the catalyst:olefin capture

followed by 1,2- or 2,1-

insertion

Stochastic simulation - how it worksStochastic simulation - how it works

Primary C attached to the catalyst:1) 1 possible isomerization 2) olefin capture and 1,2- insertion3) olefin capture and 2,1- insertion4) termination


1

2

3

4

Secondary C attached to the catalyst:1) isomerization to primary C2) isomerisation to secondary C3) olefin capture and 1,2- insertion4) olefin capture and 2,1- insertion5) termination


Secondary C attached to the catalyst:1) isomerization to secondary C2) isomerisation to secondary C3) olefin capture and 1,2- insertion4) olefin capture and 2,1- insertion5) termination


Secondary C attached to the catalyst:1) isomerization to primary C2) isomerisation to secondary C3) olefin capture and 1,2- insertion4) olefin capture and 2,1- insertion5) termination


Primary C attached to the catalyst:1) isomerization to secondary C2) olefin capture and 1,2- insertion3) olefin capture and 2,1- insertion4) termination


Primary C attached to the catalyst:1) isomerization to tertiary C2) olefin capture and 1,2- insertion3) olefin capture and 2,1- insertion4) termination


Probablities of the eventsProbablities of the events

Basic assumption:relative probabilities (microscopic)

= relative rates (macroscopic):

Basic assumption:relative probabilities (microscopic)

= relative rates (macroscopic):

i

π j

=ri

rj

i

i∑ = 1

35

Macroscopic kinetic expressions with microscopic barriers for elementary reactions(calculated or experimental)

Macroscopic kinetic expressions with microscopic barriers for elementary reactions(calculated or experimental)

Use of macroscopic kinetic expressions allows us to discuss the effects of the reaction conditions (temperature and olefin pressure)

Use of macroscopic kinetic expressions allows us to discuss the effects of the reaction conditions (temperature and olefin pressure)

Propylene polymerization (theoretical data)Propylene polymerization (theoretical data)

R = H; Ar = H

CC

NN

Pd

A. Michalak, T. Ziegler, „Stochastic modelling of the propylene polymerization catalyzed by the Pd-based diimine catalyst: influence of the catalyst structure and the reaction conditions on the polymer microstructure”, J. Am. Chem. Soc, 2002, in press.

R=H; Ar= Ph

CC

CCCC

CNN CCC

CCC C

Pd


R=An; Ar= Ph(i-Pr)2

CCC

CC

CC

C

C

CC

C

CC

C

CC

C

C

CC

C

N CNC CC

C

C

CCC C

CC

Pd

CC


220

240

260

280

300

320

0 100 200 300 400 500

T [K]

No. of branches / 1000 C

Propylene polymerization - temperature effectPropylene polymerization - temperature effect

T=98K

T=198K

T=298K

T=398K

T=498K

39

C

CC

C

C

CC

C

CC

C

CC

C

C

N CNC CC

CC

C

C C

CC

Pd

CC

220

240

260

280

300

320

0 100 200 300 400 500

T [K]

No. of branches / 1000 C

Propylene polymerization - temperature effectPropylene polymerization - temperature effect

T=98K

T=198K

T=298K

T=398K

T=498K

40

C

CC

C

C

CC

C

CC

C

CC

C

C

N CNC CC

CC

C

C C

CC

Pd

CC

• Two insertion pathways: 1,2- i 2,1-

• Chain straightening follows 2,1-insertion only

•Lower barrier for the 1,2-insertion (by c.a. 0.6 kcal/mol)

• Practically each 2,1-insertion is followed by chain straighening

220

240

260

280

300

320

0.001 0.01 0.1 1

p [ arbitrary units]

No. of branches

Propylene polymerization - pressure effectPropylene polymerization - pressure effect41

C

CC

C

C

CC

C

CC

C

CC

C

C

N CNC CC

CC

C

C C

CC

Pd

CC

220

240

260

280

300

320

0.001 0.01 0.1 1


No. of branches

Propylene polymerization - pressure effectPropylene polymerization - pressure effect42

C

CC

C

C

CC

C

CC

C

CC

C

C

N CNC CC

CC

C

C C

CC

Pd

CC

Exp.: 213br. / 1000 C

„Ideal” – no chain straighening333.3

Propylene polymerization - pressure effectPropylene polymerization - pressure effect

p=0.1

p=0.01

p=0.001

p=0.0001

43

C

CC

C

C

CC

C

CC

C

CC

C

C

N CNC CC

CC

C

C C

CC

Pd

CC

Ethylene polymerization by Pd-based diimine catalyst Simulations from experimental data (G)

Ethylene polymerization by Pd-based diimine catalyst Simulations from experimental data (G)

44

CCC

CC

CC

C

C

CC

C

CC

C

CC

C

C

CC

C

N CNC CC

C

C

CCC C

CC

Pd

CC

0

30

60

90

120

150

0.001 0.01 0.1 1


No. of branches

Ethylene polymerization by Pd-based diimine catalyst Simulations from experimental data


45

CCC

CC

CC

C

C

CC

C

CC

C

CC

C

C

CC

C

N CNC CC

C

C

CCC C

CC

Pd

CC

Exp.



46

p

Ethylene polymerization - model studies on the effects of catalyst (elementary reaction barriers), temperature, and pressure on the

microstructure of polymers

Ethylene polymerization - model studies on the effects of catalyst (elementary reaction barriers), temperature, and pressure on the

microstructure of polymers

47

Ethylene polymerization - pressure / catalyst effects


0

50

100

150

200

250

300

350

0.0001 0.001 0.01 0.1 1

E2=1E2=2E2=3E2=4E2=5E2=6E2=7E2=8E2=9N

o. o

f b

ran

ches

/ 10

00 C

p [arbitrary units]

E1=1.0 kcal/mol

48



0

50

100

150

200

250

300

350

0.0001 0.001 0.01 0.1 1

E2=1E2=2E2=3E2=4E2=5E2=6E2=7E2=8E2=9N

o. o

f b

ran

ches

/ 10

00 C

p [arbitrary units]

E1=1.0 kcal/mol

49

pressure independent region

0

50

100

150

200

250

300

350

400

450

0.0001 0.001 0.01 0.1 1

E1=2.0 kcal/mol

0

50100

150200

250

300350

400450

500

0.0001 0.001 0.01 0.1 1

E1=3.0 kcal/mol

0

100

200

300

400

500

600

0.0001 0.001 0.01 0.1 1

E1=4.0 kcal/mol

0

100

200

300

400

500

600

0.0001 0.001 0.01 0.1 1

E1=6.0 kcal/mol

50

The faster is the isomerisation (compared to insertions), the more extended is the pressure independent region.

The faster is the isomerisation (compared to insertions), the more extended is the pressure independent region.For Ni-diimine catalyst the isomerisation is slower then for Pdi.e. for Pd the pressure independent region is more extended toward higher values of the pressure

For Ni-diimine catalyst the isomerisation is slower then for Pdi.e. for Pd the pressure independent region is more extended toward higher values of the pressure

The polyethylene galleryThe polyethylene gallery

E1E2=2 kcal/mol

E1E2=5 kcal/mol

E1E2=7 kcal/mol

E1E2=5 kcal/mol

E1E2=5 kcal/mol

p=0.0001; T=298 K

51

Ethylene polymerization with the Ethylene polymerization with the neutral anilinotropone Ni-based neutral anilinotropone Ni-based

catalystcatalyst


catalystcatalyst

Experimental data:

Hiks, F.A., Brookhart M.

Organometallics 2001, 20, 3217.

Experimental data:




catalystcatalyst


catalystcatalyst

Experimental data:



Experimental data:



0

20

40

60

80

100

120

0 100 200 300 400 500 600 700

p [psig]

br./1000C

0

10

20

30

40

50

60

70

80

20 40 60 80 100 120

T [C]

br./1000C

0

5

10

-5

-10

-15

-20N-isomers

O-isomers

Alkyl

AlkylAlkyl

Alkyl

-

-

- -

ins. TS

ins. TS ins. TS

ins. TS

iso. TS

iso. TS

1.9

-12.9

-17.9

0.01.9

9.5

5.8

1.33.4

-17.5-17.1

5.7

1.7

Secondary alkyl Primary alkyl

Ni-anilinotropone catalyst – results for real catalyst

0

20

40

60

80

100

120

140

160

0 0.0038 0.0076 0.0114 0.0152 0.019 0.0228

p [arb.u.]

br./1000C

14 50 100 200 400 600p [psig]

Ni-anilinotropone catalyst – stochastic simulations

Theoret.

Exp.

0102030405060708090

100

40 50 60 70 80 90 100

T [C]

br./1000C

p = 0.011 arb.u. / p = 400 psig

Theoret.

Exp.

Ni-anilinotropone catalyst – stochastic simulations

Polar copolymerization – diimine catalysts

Copolymerization of -olefins with methyl acrylate

N^N-Pd+ - activeN^N-Ni+ - inactive (???)


Copolymerization mechanism – acrylate insertionCopolymerization mechanism – acrylate insertion

A. Michalak, T. Ziegler, „DFT Studies on the Copolymerization of -Olefins with Polar Monomers: Ethylene-Methyl Acrylate Copolymerization Catalyzed by a Pd-based Diimine Catalyst” , J. Am. Chem. Soc, 123, 2001, 12266-12278.

0

-10

-5

-15

-20

-25

-30

-35

-40

alkyl agostic+acrylate

acrylate complex

insertion TS

-agostic

-agostic

4-memb. chelate

5-memb. chelate

6-memb. chelate

-20.7

+19.4

-18.5

-5.3

-8.5

-6.1

-1.1

-20.7

CC

C

NN

O

O

C

Pd

C

CC

C

C

C C

N N

Pd

CO

C

C

C

C

C

OC

C C

C

N N

C

Pd

C

CO

C

C

CO

C C

N N

Pd

CO

C

C

C

C

C

C

O

C C

N N

Pd

C

C

O

C

C

C

C

C

O

C C

N N

PdO

C

C

C

CC

O

CC

CC

NN

Pd

C C

C

O

CC

C

C

O

kcal/mol

Acrylate insertion (2,1-) – Pd catalystAcrylate insertion (2,1-) – Pd catalyst

0

-10

-5

-15

-20

-25

-30

-35

-40

alkyl agostic+acrylate

acrylate complex

insertion TS

-agostic

-agostic

4-memb. chelate

5-memb. chelate

6-memb. chelate

CC

C

NN

O

O

C

Pd

C

CC

C

C

C C

N N

Pd

CO

C

C

C

C

C

OC

C C

C

N N

C

Pd

C

CO

C

C

CO

C C

N N

Pd

CO

C

C

C

C

C

C

O

C C

N N

Pd

C

C

O

C

C

C

C

C

O

C C

N N

PdO

C

C

C

CC

O

CC

CC

NN

Pd

C C

C

O

CC

C

C

O

kcal/mol

Acrylate insertion (2,1-) - Pd and Ni catalystsAcrylate insertion (2,1-) - Pd and Ni catalysts

Chelate opening: ethylene insertionChelate opening: ethylene insertion

Two-step chelate openingTwo-step chelate opening

very high insertion barrierslower for Ni-catalyst

Ni – high barrier (higher than insertion)Pd – low barrier (lower than insertion)

low insertion barriers,lower for Ni-catalyst

Two-step chelate openingTwo-step chelate opening

very high insertion barrierslower for Ni-catalyst

Ni – high barrier (higher than insertion)Pd – low barrier (lower than insertion)


A. Michalak, T. Ziegler, „First-principle MD studies on the methyl acrylate – ethylene copolymerization: comparison of the Ni and Pd-based diimine catalysts”, in preparation


A. Michalak, T. Ziegler, „First-principle MD studies on the methyl acrylate – ethylene copolymerization: comparison of the Ni and Pd-based diimine catalysts”, in preparation

Copolymerization mechanism– catalyst-monomer complexes

Copolymerization mechanism– catalyst-monomer complexes

A. Michalak, T. Ziegler, „DFT Studies on the Copolymerization of a-Olefins with Polar Monomers: Comonomer Binding by Nickel- and Palladium-Based Catalysts with Brookhart and Grubbs Ligands”, Organometallics, 20, 2001, 1521-1532.

A. Michalak, T. Ziegler, „Molecular Dynamics Studies of the Interconversion Between Oxygen- and Olefin-bound Methyl Acrylate in Nickel- and Palladium-based Diimine Complexes. Implications for the Copolymerization of a-Olefins with Polar Monomers”, in preparation

A. Michalak, T. Ziegler, „DFT Studies on the Copolymerization of a-Olefins with Polar Monomers: Comonomer Binding by Nickel- and Palladium-Based Catalysts with Brookhart and Grubbs Ligands”, Organometallics, 20, 2001, 1521-1532.

A. Michalak, T. Ziegler, „Molecular Dynamics Studies of the Interconversion Between Oxygen- and Olefin-bound Methyl Acrylate in Nickel- and Palladium-based Diimine Complexes. Implications for the Copolymerization of a-Olefins with Polar Monomers”, in preparation

Ni- (inactive):O-complex preferred

Pd- (active) -complex preferred

Preference of the - / O- complex - theoretical catalyst screening test

- / O- complexes- / O- complexes

- / O- complexes- / O- complexes

Methyl acrylate: molecular electrostatic potential

Electrostatic origin of the O-complex preferrence for Ni-system

Table 1. The monomer binding energies for the generic models for the Ni- and Pd-based Brookhart and Grubbs catalysts.

Catalyst Monomer E (C=C)1 E (O)2 E(C=C) - E(O)2

1a. Brookhart/Ni MA -17.10 -21.10 +4.001b. Brokhart/Pd MA -20.70 -17.30 -3.40

1a. Brookhart/Ni VA -17.07 -17.75 +0.681b. Brokhart/Pd VA -20.12 -14.96 -5.16

1a. Brookhart/Ni FMA -13.93 -16.25 +2.321b. Brokhart/Pd FMA -17.95 -12.92 -5.03

1a. Brookhart/Ni FVA -11.41 -9.99 -1.421b. Brokhart/Pd FVA -14.76 -8.10 -6.66

3a. Grubbs/Ni MA -17.74 -10.18 -7.563b. Grubbs/Pd MA -24.34 -10.17 -14.17

3a. Grubbs/Ni VA -16.09 -9.72 -7.183b. Grubbs/Pd VA -21.72 -9.56 -12.16

1 -complex stabilization energy, in kcal/mol;2 stabilization energy of the O-complex, in kcal/mol;3 the difference in the energies of the -complex and O-complex;

Table 1. The monomer binding energies for the generic models for the Ni- and Pd-based Brookhart and Grubbs catalysts.

Catalyst Monomer E (C=C)1 E (O)2 E(C=C) - E(O)2

1a. Brookhart/Ni MA -17.10 -21.10 +4.001b. Brokhart/Pd MA -20.70 -17.30 -3.40

1a. Brookhart/Ni VA -17.07 -17.75 +0.681b. Brokhart/Pd VA -20.12 -14.96 -5.16

1a. Brookhart/Ni FMA -13.93 -16.25 +2.321b. Brokhart/Pd FMA -17.95 -12.92 -5.03

1a. Brookhart/Ni FVA -11.41 -9.99 -1.421b. Brokhart/Pd FVA -14.76 -8.10 -6.66

3a. Grubbs/Ni MA -17.74 -10.18 -7.563b. Grubbs/Pd MA -24.34 -10.17 -14.17

3a. Grubbs/Ni VA -16.09 -9.72 -7.183b. Grubbs/Pd VA -21.72 -9.56 -12.16

1 -complex stabilization energy, in kcal/mol;2 stabilization energy of the O-complex, in kcal/mol;3 the difference in the energies of the -complex and O-complex;

1a (Ni)1a (Ni)

1b (Pd)1b (Pd)

Fig 1. MA - and O-complexes with diimine catalysts

Copolymerization of ethylene with methyl acrylateCopolymerization of ethylene with methyl acrylate

• Ni-catalyst poissoned at lower temperatures by formation of the O-complexes and chelates

• Chelate opening has to happen prior to ethylene insertion (at the -complex stage);

• Electrostatic origin of the O-complex stability for the Ni-catalyst suggests use of neutral complexes

• Ni-catalyst poissoned at lower temperatures by formation of the O-complexes and chelates

• Chelate opening has to happen prior to ethylene insertion (at the -complex stage);

• Electrostatic origin of the O-complex stability for the Ni-catalyst suggests use of neutral complexes

theoretical studies on the polymerization and copolymerization processes catalyzed by the late...

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ph me2 r

ph ipr2models

ph ipr2 r2

different substituents

variety of systems

generic system

reaction conditions

copolymerization processes