Organolanthanide-catalyzed synthesis of phosphine-terminated polyethylenes. Scope and mechanism

Amber M. Kawaoka, Tobin J Marks

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

Primary and secondary phosphines are investigated as chain-transfer agents for organolanthanide-mediated olefin polymerization. Ethylene polymerizations were carried out with [Cp′2LnH]2 and Cp′2-LnCH(SiMe3)2 (Cp′ = η5-Me5C5; Ln = La, Sm, Y, Lu) precatalysts in the presence of dicyclohexyl-, diisobutyl-, diethyl-, diphenyl-, cyclohexyl-, and phenylphosphine. In the presence of secondary phosphines, high polymerization activities (up to 107 g of polymer/(mol of Ln·atm ethylene·h)) and narrow product polymer polydispersities are observed. For lanthanocene-mediated ethylene polymerizations, the phosphine chain-transfer efficiency correlates with the rate of Ln-CH(SiMe 3)2 protonolysis by the same phosphines and follows the trend H2PPh ≫ H2PCy > HPPh2 > HPEt2 ≈ HP′Bu2 > HPCy2. Under the conditions investigated, dicyclohexylphosphine is not an efficient chain-transfer agent for Cp′2LaPCy2- and Cp′2YPCy2-mediated ethylene polymerizations. Diisobutylphosphine and diethylphosphine are efficient chain-transfer agents for Cp′2La-mediated polymerizations; however, phosphine chain transfer does not appear to be competitive with other chain-transfer pathways in Cp′2Y-mediated polymerizations involving diisobutylphosphine. Regardless of the lanthanide metal, diphenylphosphine is an efficient chain-transfer agent for ethylene polymerization. Polymerizations conducted in the presence of primary phosphines produce only low-molecular-weight products. Thus, Cp′2Y-mediated ethylene polymerizations conducted in the presence of phenylphosphine and cyclohexylphosphine produce low-molecular-weight phenylphosphine- and cyclohexylphosphine-capped oligomers, respectively. For Cp′2YPPh2-mediated ethylene polymerizations, a linear relationship is observed between Mn and [diphenylphosphine] -1, consistent with a phosphine protonolytic chain-transfer mechanism.

Original languageEnglish
Pages (from-to)6311-6324
Number of pages14
JournalJournal of the American Chemical Society
Volume127
Issue number17
DOIs
Publication statusPublished - May 4 2005

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phosphine
Polyethylenes
Polymerization
Phosphines
Ethylene
Polymers
Molecular Weight
Molecular weight

ASJC Scopus subject areas

  • Chemistry(all)

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Organolanthanide-catalyzed synthesis of phosphine-terminated polyethylenes. Scope and mechanism. / Kawaoka, Amber M.; Marks, Tobin J.

In: Journal of the American Chemical Society, Vol. 127, No. 17, 04.05.2005, p. 6311-6324.

Research output: Contribution to journalArticle

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abstract = "Primary and secondary phosphines are investigated as chain-transfer agents for organolanthanide-mediated olefin polymerization. Ethylene polymerizations were carried out with [Cp′2LnH]2 and Cp′2-LnCH(SiMe3)2 (Cp′ = η5-Me5C5; Ln = La, Sm, Y, Lu) precatalysts in the presence of dicyclohexyl-, diisobutyl-, diethyl-, diphenyl-, cyclohexyl-, and phenylphosphine. In the presence of secondary phosphines, high polymerization activities (up to 107 g of polymer/(mol of Ln·atm ethylene·h)) and narrow product polymer polydispersities are observed. For lanthanocene-mediated ethylene polymerizations, the phosphine chain-transfer efficiency correlates with the rate of Ln-CH(SiMe 3)2 protonolysis by the same phosphines and follows the trend H2PPh ≫ H2PCy > HPPh2 > HPEt2 ≈ HP′Bu2 > HPCy2. Under the conditions investigated, dicyclohexylphosphine is not an efficient chain-transfer agent for Cp′2LaPCy2- and Cp′2YPCy2-mediated ethylene polymerizations. Diisobutylphosphine and diethylphosphine are efficient chain-transfer agents for Cp′2La-mediated polymerizations; however, phosphine chain transfer does not appear to be competitive with other chain-transfer pathways in Cp′2Y-mediated polymerizations involving diisobutylphosphine. Regardless of the lanthanide metal, diphenylphosphine is an efficient chain-transfer agent for ethylene polymerization. Polymerizations conducted in the presence of primary phosphines produce only low-molecular-weight products. Thus, Cp′2Y-mediated ethylene polymerizations conducted in the presence of phenylphosphine and cyclohexylphosphine produce low-molecular-weight phenylphosphine- and cyclohexylphosphine-capped oligomers, respectively. For Cp′2YPPh2-mediated ethylene polymerizations, a linear relationship is observed between Mn and [diphenylphosphine] -1, consistent with a phosphine protonolytic chain-transfer mechanism.",
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N2 - Primary and secondary phosphines are investigated as chain-transfer agents for organolanthanide-mediated olefin polymerization. Ethylene polymerizations were carried out with [Cp′2LnH]2 and Cp′2-LnCH(SiMe3)2 (Cp′ = η5-Me5C5; Ln = La, Sm, Y, Lu) precatalysts in the presence of dicyclohexyl-, diisobutyl-, diethyl-, diphenyl-, cyclohexyl-, and phenylphosphine. In the presence of secondary phosphines, high polymerization activities (up to 107 g of polymer/(mol of Ln·atm ethylene·h)) and narrow product polymer polydispersities are observed. For lanthanocene-mediated ethylene polymerizations, the phosphine chain-transfer efficiency correlates with the rate of Ln-CH(SiMe 3)2 protonolysis by the same phosphines and follows the trend H2PPh ≫ H2PCy > HPPh2 > HPEt2 ≈ HP′Bu2 > HPCy2. Under the conditions investigated, dicyclohexylphosphine is not an efficient chain-transfer agent for Cp′2LaPCy2- and Cp′2YPCy2-mediated ethylene polymerizations. Diisobutylphosphine and diethylphosphine are efficient chain-transfer agents for Cp′2La-mediated polymerizations; however, phosphine chain transfer does not appear to be competitive with other chain-transfer pathways in Cp′2Y-mediated polymerizations involving diisobutylphosphine. Regardless of the lanthanide metal, diphenylphosphine is an efficient chain-transfer agent for ethylene polymerization. Polymerizations conducted in the presence of primary phosphines produce only low-molecular-weight products. Thus, Cp′2Y-mediated ethylene polymerizations conducted in the presence of phenylphosphine and cyclohexylphosphine produce low-molecular-weight phenylphosphine- and cyclohexylphosphine-capped oligomers, respectively. For Cp′2YPPh2-mediated ethylene polymerizations, a linear relationship is observed between Mn and [diphenylphosphine] -1, consistent with a phosphine protonolytic chain-transfer mechanism.

AB - Primary and secondary phosphines are investigated as chain-transfer agents for organolanthanide-mediated olefin polymerization. Ethylene polymerizations were carried out with [Cp′2LnH]2 and Cp′2-LnCH(SiMe3)2 (Cp′ = η5-Me5C5; Ln = La, Sm, Y, Lu) precatalysts in the presence of dicyclohexyl-, diisobutyl-, diethyl-, diphenyl-, cyclohexyl-, and phenylphosphine. In the presence of secondary phosphines, high polymerization activities (up to 107 g of polymer/(mol of Ln·atm ethylene·h)) and narrow product polymer polydispersities are observed. For lanthanocene-mediated ethylene polymerizations, the phosphine chain-transfer efficiency correlates with the rate of Ln-CH(SiMe 3)2 protonolysis by the same phosphines and follows the trend H2PPh ≫ H2PCy > HPPh2 > HPEt2 ≈ HP′Bu2 > HPCy2. Under the conditions investigated, dicyclohexylphosphine is not an efficient chain-transfer agent for Cp′2LaPCy2- and Cp′2YPCy2-mediated ethylene polymerizations. Diisobutylphosphine and diethylphosphine are efficient chain-transfer agents for Cp′2La-mediated polymerizations; however, phosphine chain transfer does not appear to be competitive with other chain-transfer pathways in Cp′2Y-mediated polymerizations involving diisobutylphosphine. Regardless of the lanthanide metal, diphenylphosphine is an efficient chain-transfer agent for ethylene polymerization. Polymerizations conducted in the presence of primary phosphines produce only low-molecular-weight products. Thus, Cp′2Y-mediated ethylene polymerizations conducted in the presence of phenylphosphine and cyclohexylphosphine produce low-molecular-weight phenylphosphine- and cyclohexylphosphine-capped oligomers, respectively. For Cp′2YPPh2-mediated ethylene polymerizations, a linear relationship is observed between Mn and [diphenylphosphine] -1, consistent with a phosphine protonolytic chain-transfer mechanism.

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