Theoretical studies on the polymerization and copolymerization processes catalyzed by the late transition metal complexes Artur Michalak a,b and Tom Ziegler.

Theoretical studies on the polymerization and copolymerization processes catalyzed by the late transition metal complexes Artur Michalak a,b and Tom Ziegler a a Department of Chemistry, University of Calgary, Calgary, Alberta, Canada b Department of Theoretical Chemistry Jagiellonian University Cracow, Poland Artur Michalak a,b and Tom Ziegler a a Department of Chemistry, University of Calgary, Calgary, Alberta, Canada b Department of Theoretical Chemistry Jagiellonian University Cracow, Poland April 3, 2002

Outline 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

Outline 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 mechanism  -agostic  -complex + ethylene  -agostic  -agostic insertion

Chain isomerization  -olefin polymerization mechanism

Diimine catalysts

Influence of olefin pressure on the polymer structure high p - linear structures low p - hyperbranched structures Pd – No. of branches independent of p Ni – No. of braches influenced by p

 -olefin polymerization mechanism

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

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/mol exp.: 17.4 kcal/mol Isomerization barrier: DFT: 5.8-6.8 kcal/mol exp: 7.2 kcal/mol

Substituent effect in real systems Electronic preference Steric effect (generic system) (real systems) alkyl complexesiso-propyl iso-propyl olefin  -complexesiso-propyl alkyl n-propyl alkyl olefin  -complexespropene ethene propene insertion2,1- 1,2- Electronic preference Steric effect (generic system) (real systems) alkyl complexesiso-propyl iso-propyl olefin  -complexesiso-propyl alkyl n-propyl alkyl olefin  -complexespropene ethene propene insertion2,1- 1,2-

Isomerization reactions 0.00 +4.56 -3.42 0.00 +5.84 +1.59 following 1,2-insertion following 2,1-insertion

1 C atom attached to the catalyst: olefin capture followed by 1,2- or 2,1- insertion Stochastic simulation - how it works

Primary C attached to the catalyst: 1) 1 possible isomerization 2) olefin capture and 1,2- insertion 3) olefin capture and 2,1- insertion 4) termination Stochastic simulation - how it works 1 2 3 4

Secondary C attached to the catalyst: 1) isomerization to primary C 2) isomerisation to secondary C 3) olefin capture and 1,2- insertion 4) olefin capture and 2,1- insertion 5) termination Stochastic simulation - how it works

Secondary C attached to the catalyst: 1) isomerization to secondary C 2) isomerisation to secondary C 3) olefin capture and 1,2- insertion 4) olefin capture and 2,1- insertion 5) termination Stochastic simulation - how it works

Secondary C attached to the catalyst: 1) isomerization to primary C 2) isomerisation to secondary C 3) olefin capture and 1,2- insertion 4) olefin capture and 2,1- insertion 5) termination Stochastic simulation - how it works

Primary C attached to the catalyst: 1) isomerization to secondary C 2) olefin capture and 1,2- insertion 3) olefin capture and 2,1- insertion 4) termination Stochastic simulation - how it works

Primary C attached to the catalyst: 1) isomerization to tertiary C 2) olefin capture and 1,2- insertion 3) olefin capture and 2,1- insertion 4) termination Stochastic simulation - how it works

Probablities of the events Basic assumption: relative probabilities (microscopic) = relative rates (macroscopic): Basic assumption: relative probabilities (microscopic) = relative rates (macroscopic): 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) R = H; Ar = H  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 Propylene polymerization (theoretical data)

R=An; Ar= Ph(i-Pr) 2 Propylene polymerization (theoretical data)

Propylene polymerization - temperature effect T=98K T=198K T=298K T=398K T=498K 39

Propylene polymerization - temperature effect T=98K T=198K T=298K T=398K T=498K 40 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

Propylene polymerization - pressure effect 41

Propylene polymerization - pressure effect 42 Exp.: 213br. / 1000 C „Ideal” – no chain straighening 333.3

Propylene polymerization - pressure effect p=0.1 p=0.01 p=0.001 p=0.0001 43

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

Ethylene polymerization by Pd-based diimine catalyst Simulations from experimental data Ethylene polymerization by Pd-based diimine catalyst Simulations from experimental data 45 Exp.

Ethylene polymerization by Pd-based diimine catalyst Simulations from experimental data Ethylene polymerization by Pd-based diimine catalyst Simulations from experimental data 46 p

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 Ethylene polymerization - pressure / catalyst effects 0 50 100 150 200 250 300 350 0.00010.0010.010.11  E 2 =1  E 2 =2  E 2 =3  E 2 =4  E 2 =5  E 2 =6  E 2 =7  E 2 =8  E 2 =9 No. of branches / 1000 C p [arbitrary units]  E 1 =1.0 kcal/mol 48

Ethylene polymerization - pressure / catalyst effects Ethylene polymerization - pressure / catalyst effects 0 50 100 150 200 250 300 350 0.00010.0010.010.11  E 2 =1  E 2 =2  E 2 =3  E 2 =4  E 2 =5  E 2 =6  E 2 =7  E 2 =8  E 2 =9 No. of branches / 1000 C p [arbitrary units]  E 1 =1.0 kcal/mol 49 pressure independent region

 E 1 =2.0 kcal/mol  E 1 =3.0 kcal/mol  E 1 =4.0 kcal/mol  E 1 =6.0 kcal/mol 50 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 Pd i.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 Pd i.e. for Pd the pressure independent region is more extended toward higher values of the pressure

The polyethylene gallery  E 1  E 2 =2 kcal/mol  E 1  E 2 =5 kcal/mol  E 1  E 2 =7 kcal/mol  E 1  E 2 =5 kcal/mol  E 1  E 2 =5 kcal/mol p=0.0001; T=298 K 51

Ethylene polymerization with the neutral anilinotropone Ni-based catalyst Experimental data: Hiks, F.A., Brookhart M. Organometallics 2001, 20, 3217. Experimental data: Hiks, F.A., Brookhart M. Organometallics 2001, 20, 3217.

0 5 10 -5 -10 -15 -20 N-isomers O-isomers Alkyl -- -- -- -- ins. TS iso. TS 1.9 -12.9 -17.9 0.0 1.9 9.5 5.8 1.3 3.4 -17.5 -17.1 5.7 1.7 Secondary alkylPrimary alkyl Ni-anilinotropone catalyst – results for real catalyst

14 50 100 200400 600 p [psig] Ni-anilinotropone catalyst – stochastic simulations Theoret. Exp.

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 + - active N^N-Ni + - inactive (???) Diimine catalysts

Copolymerization 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.

Acrylate insertion (2,1-) – Pd catalyst

0 -10 -5 -15 -20 -25 -30 -35 -40 alkyl agostic +acrylate acrylate   complex insertion TS  -agostic  4-memb. chelate 5-memb. chelate 6-memb. chelate C C C NN O O C Pd C C C C C CC NN C O C C C C C O C CC C NN C C C O C C C O C C N N C O C C C C C C O CC N N C C O C C C C C O C C N N O C C C C C O C C CC NN C C C O C C C C O kcal/mol Acrylate insertion (2,1-) - Pd and Ni catalysts

Chelate opening: ethylene insertion

Two-step chelate opening very high insertion barriers lower 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 opening very high insertion barriers lower for Ni-catalyst Ni – high barrier (higher than insertion) Pd – low barrier (lower than 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.  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, „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.  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

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. CatalystMonomer  E (C=C) 1  E (O) 2 E(C=C) - E(O) 2 1a. Brookhart/NiMA-17.10-21.10 +4.00 1b. Brokhart/PdMA-20.70-17.30 -3.40 1a. Brookhart/NiVA-17.07-17.75 +0.68 1b. Brokhart/PdVA-20.12-14.96 -5.16 1a. Brookhart/NiFMA-13.93-16.25 +2.32 1b. Brokhart/PdFMA-17.95-12.92 -5.03 1a. Brookhart/NiFVA-11.41 -9.99 -1.42 1b. Brokhart/PdFVA-14.76 -8.10 -6.66 3a. Grubbs/NiMA-17.74-10.18 -7.56 3b. Grubbs/PdMA-24.34-10.17-14.17 3a. Grubbs/NiVA-16.09 -9.72 -7.18 3b. Grubbs/PdVA-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. CatalystMonomer  E (C=C) 1  E (O) 2 E(C=C) - E(O) 2 1a. Brookhart/NiMA-17.10-21.10 +4.00 1b. Brokhart/PdMA-20.70-17.30 -3.40 1a. Brookhart/NiVA-17.07-17.75 +0.68 1b. Brokhart/PdVA-20.12-14.96 -5.16 1a. Brookhart/NiFMA-13.93-16.25 +2.32 1b. Brokhart/PdFMA-17.95-12.92 -5.03 1a. Brookhart/NiFVA-11.41 -9.99 -1.42 1b. Brokhart/PdFVA-14.76 -8.10 -6.66 3a. Grubbs/NiMA-17.74-10.18 -7.56 3b. Grubbs/PdMA-24.34-10.17-14.17 3a. Grubbs/NiVA-16.09 -9.72 -7.18 3b. Grubbs/PdVA-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) 1b (Pd)   Fig 1. MA  - and O-complexes with diimine catalysts  

Copolymerization 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 transition metal complexes Artur Michalak a,b and Tom Ziegler.

Similar presentations

Presentation on theme: "Theoretical studies on the polymerization and copolymerization processes catalyzed by the late transition metal complexes Artur Michalak a,b and Tom Ziegler."— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Theoretical studies on the polymerization and copolymerization processes catalyzed by the late transition metal complexes Artur Michalak a,b and Tom Ziegler.

Similar presentations

Presentation on theme: "Theoretical studies on the polymerization and copolymerization processes catalyzed by the late transition metal complexes Artur Michalak a,b and Tom Ziegler."— Presentation transcript:

Similar presentations

About project

Feedback