Ligand and solvent effects in the alternating copolymerization of carbon monoxide and olefins by palladium-diphosphine catalysis

Claudio Bianchini, Hon Man Lee, Andrea Meli, Werner Oberhauser, Maurizio Peruzzini, Francesco Vizza

Research output: Contribution to journalArticle

72 Citations (Scopus)

Abstract

The substitution of two hydrogen atoms by methyl groups in the 1,2 positions of 1,2-bis-(diphenylphosphino)ethane (dppe) gives meso- and rac-2,3-bis(diphenylphosphino)butane (meso-2,3-dppb and rac-2,3-dppb). The corresponding Pd(II) complexes Pd(OTs)2(meso-2,3-dppb) and Pd(OTs)2(rac-2,3-dppb) are effective catalyst precursors for the alternating copolymerization and terpolymerization of carbon monoxide with ethene and ethene/propene in MeOH with productivities that are higher than those of the unsubstituted dppe catalyst Pd(OTs)2(dppe) even by a factor of 10 (OTs = p-toluenesulfonate). It has been found that the low productivity of the dppe-based catalyst in MeOH is due to the autoionization of the precursor Pd(OAc)2(dppe) in MeOH to give the catalytically inactive bis-chelate species [Pd-(dppe)2](OAc)2 and palladium acetate. In an attempt to evaluate and rationalize the effective ligand control on the intrinsic catalytic activity, the methyl complexes [Pd(Me)(MeCN)(P-P)]PF 6 have been synthesized and employed in CH2Cl2 to catalyze the alternating carbon monoxide/ethene copolymerization. The intrinsic activity of the three precursors decreases in the order [Pd(Me)(MeCN)(meso-2,3-dppb)]+ > [Pd(Me)(MeCN)(rac-2,3-dppb)] + > [Pd(Me)-(MeCN)(dppe)]+. High-pressure NMR experiments and the determination of activation barriers of migratory insertions agree to indicate the relative stability of the β-chelate ring in [Pd(CH2CH2C(O)Me)(P-P)]+ as the factor that controls the copolymerization rate in aprotic solvents. The impact of the different diphosphines on both productivity and intrinsic catalytic activity has been attributed to the different stereochemical rigidity of the Pd(P-P) five-membered metallarings. The β-chelate complexes [Pd(CH 2CH2C(O)Me)(P-P)]PF6 with diphosphine ligands containing two carbon atoms between the phosphorus donors have been isolated for the first time and employed to study the chain-transfer by protonolysis, which proceeds via the enolate mechanism. It has been shown that the chain-transfer products [Pd(OH)(P-P)]22+ do not represent a dead end for the alternating CO/ethene copolymerization.

Original languageEnglish
Pages (from-to)16-33
Number of pages18
JournalOrganometallics
Volume21
Issue number1
DOIs
Publication statusPublished - 2002 Jan 1

Fingerprint

Ethane
Palladium
Alkenes
copolymerization
Carbon Monoxide
ethane
carbon monoxide
Copolymerization
Catalysis
alkenes
catalysis
palladium
ESSA 2 satellite
Ligands
ligands
productivity
chelates
Productivity
Catalysts
Catalyst activity

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

Bianchini, Claudio ; Lee, Hon Man ; Meli, Andrea ; Oberhauser, Werner ; Peruzzini, Maurizio ; Vizza, Francesco. / Ligand and solvent effects in the alternating copolymerization of carbon monoxide and olefins by palladium-diphosphine catalysis. In: Organometallics. 2002 ; Vol. 21, No. 1. pp. 16-33.
@article{7cc53d62b74347c4adea1f9c4c0ee25e,
title = "Ligand and solvent effects in the alternating copolymerization of carbon monoxide and olefins by palladium-diphosphine catalysis",
abstract = "The substitution of two hydrogen atoms by methyl groups in the 1,2 positions of 1,2-bis-(diphenylphosphino)ethane (dppe) gives meso- and rac-2,3-bis(diphenylphosphino)butane (meso-2,3-dppb and rac-2,3-dppb). The corresponding Pd(II) complexes Pd(OTs)2(meso-2,3-dppb) and Pd(OTs)2(rac-2,3-dppb) are effective catalyst precursors for the alternating copolymerization and terpolymerization of carbon monoxide with ethene and ethene/propene in MeOH with productivities that are higher than those of the unsubstituted dppe catalyst Pd(OTs)2(dppe) even by a factor of 10 (OTs = p-toluenesulfonate). It has been found that the low productivity of the dppe-based catalyst in MeOH is due to the autoionization of the precursor Pd(OAc)2(dppe) in MeOH to give the catalytically inactive bis-chelate species [Pd-(dppe)2](OAc)2 and palladium acetate. In an attempt to evaluate and rationalize the effective ligand control on the intrinsic catalytic activity, the methyl complexes [Pd(Me)(MeCN)(P-P)]PF 6 have been synthesized and employed in CH2Cl2 to catalyze the alternating carbon monoxide/ethene copolymerization. The intrinsic activity of the three precursors decreases in the order [Pd(Me)(MeCN)(meso-2,3-dppb)]+ > [Pd(Me)(MeCN)(rac-2,3-dppb)] + > [Pd(Me)-(MeCN)(dppe)]+. High-pressure NMR experiments and the determination of activation barriers of migratory insertions agree to indicate the relative stability of the β-chelate ring in [Pd(CH2CH2C(O)Me)(P-P)]+ as the factor that controls the copolymerization rate in aprotic solvents. The impact of the different diphosphines on both productivity and intrinsic catalytic activity has been attributed to the different stereochemical rigidity of the Pd(P-P) five-membered metallarings. The β-chelate complexes [Pd(CH 2CH2C(O)Me)(P-P)]PF6 with diphosphine ligands containing two carbon atoms between the phosphorus donors have been isolated for the first time and employed to study the chain-transfer by protonolysis, which proceeds via the enolate mechanism. It has been shown that the chain-transfer products [Pd(OH)(P-P)]22+ do not represent a dead end for the alternating CO/ethene copolymerization.",
author = "Claudio Bianchini and Lee, {Hon Man} and Andrea Meli and Werner Oberhauser and Maurizio Peruzzini and Francesco Vizza",
year = "2002",
month = "1",
day = "1",
doi = "10.1021/om010727b",
language = "English",
volume = "21",
pages = "16--33",
journal = "Organometallics",
issn = "0276-7333",
publisher = "American Chemical Society",
number = "1",

}

Ligand and solvent effects in the alternating copolymerization of carbon monoxide and olefins by palladium-diphosphine catalysis. / Bianchini, Claudio; Lee, Hon Man; Meli, Andrea; Oberhauser, Werner; Peruzzini, Maurizio; Vizza, Francesco.

In: Organometallics, Vol. 21, No. 1, 01.01.2002, p. 16-33.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Ligand and solvent effects in the alternating copolymerization of carbon monoxide and olefins by palladium-diphosphine catalysis

AU - Bianchini, Claudio

AU - Lee, Hon Man

AU - Meli, Andrea

AU - Oberhauser, Werner

AU - Peruzzini, Maurizio

AU - Vizza, Francesco

PY - 2002/1/1

Y1 - 2002/1/1

N2 - The substitution of two hydrogen atoms by methyl groups in the 1,2 positions of 1,2-bis-(diphenylphosphino)ethane (dppe) gives meso- and rac-2,3-bis(diphenylphosphino)butane (meso-2,3-dppb and rac-2,3-dppb). The corresponding Pd(II) complexes Pd(OTs)2(meso-2,3-dppb) and Pd(OTs)2(rac-2,3-dppb) are effective catalyst precursors for the alternating copolymerization and terpolymerization of carbon monoxide with ethene and ethene/propene in MeOH with productivities that are higher than those of the unsubstituted dppe catalyst Pd(OTs)2(dppe) even by a factor of 10 (OTs = p-toluenesulfonate). It has been found that the low productivity of the dppe-based catalyst in MeOH is due to the autoionization of the precursor Pd(OAc)2(dppe) in MeOH to give the catalytically inactive bis-chelate species [Pd-(dppe)2](OAc)2 and palladium acetate. In an attempt to evaluate and rationalize the effective ligand control on the intrinsic catalytic activity, the methyl complexes [Pd(Me)(MeCN)(P-P)]PF 6 have been synthesized and employed in CH2Cl2 to catalyze the alternating carbon monoxide/ethene copolymerization. The intrinsic activity of the three precursors decreases in the order [Pd(Me)(MeCN)(meso-2,3-dppb)]+ > [Pd(Me)(MeCN)(rac-2,3-dppb)] + > [Pd(Me)-(MeCN)(dppe)]+. High-pressure NMR experiments and the determination of activation barriers of migratory insertions agree to indicate the relative stability of the β-chelate ring in [Pd(CH2CH2C(O)Me)(P-P)]+ as the factor that controls the copolymerization rate in aprotic solvents. The impact of the different diphosphines on both productivity and intrinsic catalytic activity has been attributed to the different stereochemical rigidity of the Pd(P-P) five-membered metallarings. The β-chelate complexes [Pd(CH 2CH2C(O)Me)(P-P)]PF6 with diphosphine ligands containing two carbon atoms between the phosphorus donors have been isolated for the first time and employed to study the chain-transfer by protonolysis, which proceeds via the enolate mechanism. It has been shown that the chain-transfer products [Pd(OH)(P-P)]22+ do not represent a dead end for the alternating CO/ethene copolymerization.

AB - The substitution of two hydrogen atoms by methyl groups in the 1,2 positions of 1,2-bis-(diphenylphosphino)ethane (dppe) gives meso- and rac-2,3-bis(diphenylphosphino)butane (meso-2,3-dppb and rac-2,3-dppb). The corresponding Pd(II) complexes Pd(OTs)2(meso-2,3-dppb) and Pd(OTs)2(rac-2,3-dppb) are effective catalyst precursors for the alternating copolymerization and terpolymerization of carbon monoxide with ethene and ethene/propene in MeOH with productivities that are higher than those of the unsubstituted dppe catalyst Pd(OTs)2(dppe) even by a factor of 10 (OTs = p-toluenesulfonate). It has been found that the low productivity of the dppe-based catalyst in MeOH is due to the autoionization of the precursor Pd(OAc)2(dppe) in MeOH to give the catalytically inactive bis-chelate species [Pd-(dppe)2](OAc)2 and palladium acetate. In an attempt to evaluate and rationalize the effective ligand control on the intrinsic catalytic activity, the methyl complexes [Pd(Me)(MeCN)(P-P)]PF 6 have been synthesized and employed in CH2Cl2 to catalyze the alternating carbon monoxide/ethene copolymerization. The intrinsic activity of the three precursors decreases in the order [Pd(Me)(MeCN)(meso-2,3-dppb)]+ > [Pd(Me)(MeCN)(rac-2,3-dppb)] + > [Pd(Me)-(MeCN)(dppe)]+. High-pressure NMR experiments and the determination of activation barriers of migratory insertions agree to indicate the relative stability of the β-chelate ring in [Pd(CH2CH2C(O)Me)(P-P)]+ as the factor that controls the copolymerization rate in aprotic solvents. The impact of the different diphosphines on both productivity and intrinsic catalytic activity has been attributed to the different stereochemical rigidity of the Pd(P-P) five-membered metallarings. The β-chelate complexes [Pd(CH 2CH2C(O)Me)(P-P)]PF6 with diphosphine ligands containing two carbon atoms between the phosphorus donors have been isolated for the first time and employed to study the chain-transfer by protonolysis, which proceeds via the enolate mechanism. It has been shown that the chain-transfer products [Pd(OH)(P-P)]22+ do not represent a dead end for the alternating CO/ethene copolymerization.

UR - http://www.scopus.com/inward/record.url?scp=0002589244&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0002589244&partnerID=8YFLogxK

U2 - 10.1021/om010727b

DO - 10.1021/om010727b

M3 - Article

AN - SCOPUS:0002589244

VL - 21

SP - 16

EP - 33

JO - Organometallics

JF - Organometallics

SN - 0276-7333

IS - 1

ER -