Ring-opening Ziegler polamerization of methylenecycloalkanes catalyzed by highly electrophilic d0/f(n) metallocenes. Reactivity, scope, reaction mechanism, and routes to functionalized polyolefins

Li Jia, Xinmin Yang, Affif M. Seyam, Israel D L Albert, Peng Fei Fu, Shengtian Yang, Tobin J Marks

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Abstract

A series of zirconium and lanthanide metallocene catalysts are active in the regioselective ring-opening polymerization of strained exo-methylenecycloalkanes to yield exo-methylene-functionalized polyethylenes. MCB (methylenecyclobutane) affords the polymer [CH2CH2CH2C(CH2)](n) under the catalytic action of (1,2-Me2Cp)2ZrMe+MeB(C6F5)3-, and MCP (methylenecyclopropane) affords the polymer [CH2CH2C(CH2)](n) under the catalytic action of [(Me5Cp)2LuH]2. Reversible deactivation of the [(Me5Cp)2LuH]2 catalyst is observed in the MCP polymerization reaction and is ascribed to formation of a Lu-allyl species based on D2O quenching experiments. In contrast, the catalysts [(Me5Cp)2LuH]2 and [(Me5Cp)2LuH]2 yield the dimer 1,2-dimethylene-3-methylcyclopentane (DMP) from MCP with high chemoselectivity. The mechanism of dimerization is proposed to involve the intermediacy of 3-methylene-1,6-heptadiene (MHD) and is supported by the observation that independently synthesized MHD is smoothly converted to DMP under catalytic conditions. (Me5Cp)2ZrMe+MeB(C6F5)3- catalyzes the polymerization of MCP to a polyspirane consisting of 1,3-interlocked five-membered rings (poly(1,4:2,2-butanetetrayl), (C4H6)(n)). From end group analysis, the reaction pathway is proposed to consist of β-alkyl shift-based ring-opening followed by an intramolecular insertive, ring-closing 'zipping-up' process. AM1-level computations indicate that the zipping up reaction is exothermic by ~ 16 kcal/(mol of ring closure). Under the same catalytic conditions, the monomers methylenecyclopentane, methylenecyclohexane, and 2-methylenenorbornane undergo double bond migration (to the adjacent internal position) rather than polymerization. In contrast to the relatively restrictive requirements for homopolymerization, MCP-ethylene copolymerization is catalyzed by a wide variety of zirconocenium catalysts, including those generated conveniently from MAO, to afford high molecular weight {[CH2CH2](x)[CH2CH2CH2C(CH2)](y)}(n) copolymers with the incorporated MCB having an exclusively ring-opened microstructure. The activity of the catalysts in incorporating MCB into the polymer chain follows the order: Cp2ZrMe+>(1,2-Me2Cp)2ZrMe+≤(Me5Cp)2ZrMe+, regardless of the counteranion identity. Labeling experiments with 13CH2=13CH2 confirm that MCB ring-opening occurs with C2-C3, C2-C5 bond scission. MCP-ethylene copolymerization to yield high molecular weight {[CH2CH2](x)[CH2CH2C(CH2)](y)} having an exclusively ring-opened microstructure is catalyzed by [(Me5Cp)2LuH]2 and [(Me5Cp)2SmH]2. When [(Me5Cp)2LaH]2 is used as the catalyst, more than 50% of the MCP is located at the chain ends in a dienyl structure. The only zirconium polymerization catalyst which incorporates MCP in the ring-opened form in a moderate percentage is [(Me4CpSiMe2(N(t)Bu)]ZrMe+ B(C6F5)4-. The activity of d0/f(n) catalysts in incorporating MCP into the polymer follows the order: [(Me4CpSiMe2(N(t)Bu)]ZrMe+B(C6F5)4->[(Me5Cp)2LuH]2>[(Me5Cp) 2SmH]2>[(Me5Cp)2LaH]2.

Original languageEnglish
Pages (from-to)7900-7913
Number of pages14
JournalJournal of the American Chemical Society
Volume118
Issue number34
DOIs
Publication statusPublished - Aug 28 1996

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Polyolefins
Organometallics
Catalysts
Polymerization
Polymers
Zirconium
Copolymerization
Ethylene
Molecular weight
Polyethylenes
Molecular Weight
Microstructure
Exothermic reactions
Dimerization
methylenecyclopropane
PL 732
Lanthanoid Series Elements
Ring opening polymerization
Homopolymerization
Rare earth elements

ASJC Scopus subject areas

  • Chemistry(all)

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Ring-opening Ziegler polamerization of methylenecycloalkanes catalyzed by highly electrophilic d0/f(n) metallocenes. Reactivity, scope, reaction mechanism, and routes to functionalized polyolefins. / Jia, Li; Yang, Xinmin; Seyam, Affif M.; Albert, Israel D L; Fu, Peng Fei; Yang, Shengtian; Marks, Tobin J.

In: Journal of the American Chemical Society, Vol. 118, No. 34, 28.08.1996, p. 7900-7913.

Research output: Contribution to journalArticle

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title = "Ring-opening Ziegler polamerization of methylenecycloalkanes catalyzed by highly electrophilic d0/f(n) metallocenes. Reactivity, scope, reaction mechanism, and routes to functionalized polyolefins",
abstract = "A series of zirconium and lanthanide metallocene catalysts are active in the regioselective ring-opening polymerization of strained exo-methylenecycloalkanes to yield exo-methylene-functionalized polyethylenes. MCB (methylenecyclobutane) affords the polymer [CH2CH2CH2C(CH2)](n) under the catalytic action of (1,2-Me2Cp)2ZrMe+MeB(C6F5)3-, and MCP (methylenecyclopropane) affords the polymer [CH2CH2C(CH2)](n) under the catalytic action of [(Me5Cp)2LuH]2. Reversible deactivation of the [(Me5Cp)2LuH]2 catalyst is observed in the MCP polymerization reaction and is ascribed to formation of a Lu-allyl species based on D2O quenching experiments. In contrast, the catalysts [(Me5Cp)2LuH]2 and [(Me5Cp)2LuH]2 yield the dimer 1,2-dimethylene-3-methylcyclopentane (DMP) from MCP with high chemoselectivity. The mechanism of dimerization is proposed to involve the intermediacy of 3-methylene-1,6-heptadiene (MHD) and is supported by the observation that independently synthesized MHD is smoothly converted to DMP under catalytic conditions. (Me5Cp)2ZrMe+MeB(C6F5)3- catalyzes the polymerization of MCP to a polyspirane consisting of 1,3-interlocked five-membered rings (poly(1,4:2,2-butanetetrayl), (C4H6)(n)). From end group analysis, the reaction pathway is proposed to consist of β-alkyl shift-based ring-opening followed by an intramolecular insertive, ring-closing 'zipping-up' process. AM1-level computations indicate that the zipping up reaction is exothermic by ~ 16 kcal/(mol of ring closure). Under the same catalytic conditions, the monomers methylenecyclopentane, methylenecyclohexane, and 2-methylenenorbornane undergo double bond migration (to the adjacent internal position) rather than polymerization. In contrast to the relatively restrictive requirements for homopolymerization, MCP-ethylene copolymerization is catalyzed by a wide variety of zirconocenium catalysts, including those generated conveniently from MAO, to afford high molecular weight {[CH2CH2](x)[CH2CH2CH2C(CH2)](y)}(n) copolymers with the incorporated MCB having an exclusively ring-opened microstructure. The activity of the catalysts in incorporating MCB into the polymer chain follows the order: Cp2ZrMe+>(1,2-Me2Cp)2ZrMe+≤(Me5Cp)2ZrMe+, regardless of the counteranion identity. Labeling experiments with 13CH2=13CH2 confirm that MCB ring-opening occurs with C2-C3, C2-C5 bond scission. MCP-ethylene copolymerization to yield high molecular weight {[CH2CH2](x)[CH2CH2C(CH2)](y)} having an exclusively ring-opened microstructure is catalyzed by [(Me5Cp)2LuH]2 and [(Me5Cp)2SmH]2. When [(Me5Cp)2LaH]2 is used as the catalyst, more than 50{\%} of the MCP is located at the chain ends in a dienyl structure. The only zirconium polymerization catalyst which incorporates MCP in the ring-opened form in a moderate percentage is [(Me4CpSiMe2(N(t)Bu)]ZrMe+ B(C6F5)4-. The activity of d0/f(n) catalysts in incorporating MCP into the polymer follows the order: [(Me4CpSiMe2(N(t)Bu)]ZrMe+B(C6F5)4->[(Me5Cp)2LuH]2>[(Me5Cp) 2SmH]2>[(Me5Cp)2LaH]2.",
author = "Li Jia and Xinmin Yang and Seyam, {Affif M.} and Albert, {Israel D L} and Fu, {Peng Fei} and Shengtian Yang and Marks, {Tobin J}",
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TY - JOUR

T1 - Ring-opening Ziegler polamerization of methylenecycloalkanes catalyzed by highly electrophilic d0/f(n) metallocenes. Reactivity, scope, reaction mechanism, and routes to functionalized polyolefins

AU - Jia, Li

AU - Yang, Xinmin

AU - Seyam, Affif M.

AU - Albert, Israel D L

AU - Fu, Peng Fei

AU - Yang, Shengtian

AU - Marks, Tobin J

PY - 1996/8/28

Y1 - 1996/8/28

N2 - A series of zirconium and lanthanide metallocene catalysts are active in the regioselective ring-opening polymerization of strained exo-methylenecycloalkanes to yield exo-methylene-functionalized polyethylenes. MCB (methylenecyclobutane) affords the polymer [CH2CH2CH2C(CH2)](n) under the catalytic action of (1,2-Me2Cp)2ZrMe+MeB(C6F5)3-, and MCP (methylenecyclopropane) affords the polymer [CH2CH2C(CH2)](n) under the catalytic action of [(Me5Cp)2LuH]2. Reversible deactivation of the [(Me5Cp)2LuH]2 catalyst is observed in the MCP polymerization reaction and is ascribed to formation of a Lu-allyl species based on D2O quenching experiments. In contrast, the catalysts [(Me5Cp)2LuH]2 and [(Me5Cp)2LuH]2 yield the dimer 1,2-dimethylene-3-methylcyclopentane (DMP) from MCP with high chemoselectivity. The mechanism of dimerization is proposed to involve the intermediacy of 3-methylene-1,6-heptadiene (MHD) and is supported by the observation that independently synthesized MHD is smoothly converted to DMP under catalytic conditions. (Me5Cp)2ZrMe+MeB(C6F5)3- catalyzes the polymerization of MCP to a polyspirane consisting of 1,3-interlocked five-membered rings (poly(1,4:2,2-butanetetrayl), (C4H6)(n)). From end group analysis, the reaction pathway is proposed to consist of β-alkyl shift-based ring-opening followed by an intramolecular insertive, ring-closing 'zipping-up' process. AM1-level computations indicate that the zipping up reaction is exothermic by ~ 16 kcal/(mol of ring closure). Under the same catalytic conditions, the monomers methylenecyclopentane, methylenecyclohexane, and 2-methylenenorbornane undergo double bond migration (to the adjacent internal position) rather than polymerization. In contrast to the relatively restrictive requirements for homopolymerization, MCP-ethylene copolymerization is catalyzed by a wide variety of zirconocenium catalysts, including those generated conveniently from MAO, to afford high molecular weight {[CH2CH2](x)[CH2CH2CH2C(CH2)](y)}(n) copolymers with the incorporated MCB having an exclusively ring-opened microstructure. The activity of the catalysts in incorporating MCB into the polymer chain follows the order: Cp2ZrMe+>(1,2-Me2Cp)2ZrMe+≤(Me5Cp)2ZrMe+, regardless of the counteranion identity. Labeling experiments with 13CH2=13CH2 confirm that MCB ring-opening occurs with C2-C3, C2-C5 bond scission. MCP-ethylene copolymerization to yield high molecular weight {[CH2CH2](x)[CH2CH2C(CH2)](y)} having an exclusively ring-opened microstructure is catalyzed by [(Me5Cp)2LuH]2 and [(Me5Cp)2SmH]2. When [(Me5Cp)2LaH]2 is used as the catalyst, more than 50% of the MCP is located at the chain ends in a dienyl structure. The only zirconium polymerization catalyst which incorporates MCP in the ring-opened form in a moderate percentage is [(Me4CpSiMe2(N(t)Bu)]ZrMe+ B(C6F5)4-. The activity of d0/f(n) catalysts in incorporating MCP into the polymer follows the order: [(Me4CpSiMe2(N(t)Bu)]ZrMe+B(C6F5)4->[(Me5Cp)2LuH]2>[(Me5Cp) 2SmH]2>[(Me5Cp)2LaH]2.

AB - A series of zirconium and lanthanide metallocene catalysts are active in the regioselective ring-opening polymerization of strained exo-methylenecycloalkanes to yield exo-methylene-functionalized polyethylenes. MCB (methylenecyclobutane) affords the polymer [CH2CH2CH2C(CH2)](n) under the catalytic action of (1,2-Me2Cp)2ZrMe+MeB(C6F5)3-, and MCP (methylenecyclopropane) affords the polymer [CH2CH2C(CH2)](n) under the catalytic action of [(Me5Cp)2LuH]2. Reversible deactivation of the [(Me5Cp)2LuH]2 catalyst is observed in the MCP polymerization reaction and is ascribed to formation of a Lu-allyl species based on D2O quenching experiments. In contrast, the catalysts [(Me5Cp)2LuH]2 and [(Me5Cp)2LuH]2 yield the dimer 1,2-dimethylene-3-methylcyclopentane (DMP) from MCP with high chemoselectivity. The mechanism of dimerization is proposed to involve the intermediacy of 3-methylene-1,6-heptadiene (MHD) and is supported by the observation that independently synthesized MHD is smoothly converted to DMP under catalytic conditions. (Me5Cp)2ZrMe+MeB(C6F5)3- catalyzes the polymerization of MCP to a polyspirane consisting of 1,3-interlocked five-membered rings (poly(1,4:2,2-butanetetrayl), (C4H6)(n)). From end group analysis, the reaction pathway is proposed to consist of β-alkyl shift-based ring-opening followed by an intramolecular insertive, ring-closing 'zipping-up' process. AM1-level computations indicate that the zipping up reaction is exothermic by ~ 16 kcal/(mol of ring closure). Under the same catalytic conditions, the monomers methylenecyclopentane, methylenecyclohexane, and 2-methylenenorbornane undergo double bond migration (to the adjacent internal position) rather than polymerization. In contrast to the relatively restrictive requirements for homopolymerization, MCP-ethylene copolymerization is catalyzed by a wide variety of zirconocenium catalysts, including those generated conveniently from MAO, to afford high molecular weight {[CH2CH2](x)[CH2CH2CH2C(CH2)](y)}(n) copolymers with the incorporated MCB having an exclusively ring-opened microstructure. The activity of the catalysts in incorporating MCB into the polymer chain follows the order: Cp2ZrMe+>(1,2-Me2Cp)2ZrMe+≤(Me5Cp)2ZrMe+, regardless of the counteranion identity. Labeling experiments with 13CH2=13CH2 confirm that MCB ring-opening occurs with C2-C3, C2-C5 bond scission. MCP-ethylene copolymerization to yield high molecular weight {[CH2CH2](x)[CH2CH2C(CH2)](y)} having an exclusively ring-opened microstructure is catalyzed by [(Me5Cp)2LuH]2 and [(Me5Cp)2SmH]2. When [(Me5Cp)2LaH]2 is used as the catalyst, more than 50% of the MCP is located at the chain ends in a dienyl structure. The only zirconium polymerization catalyst which incorporates MCP in the ring-opened form in a moderate percentage is [(Me4CpSiMe2(N(t)Bu)]ZrMe+ B(C6F5)4-. The activity of d0/f(n) catalysts in incorporating MCP into the polymer follows the order: [(Me4CpSiMe2(N(t)Bu)]ZrMe+B(C6F5)4->[(Me5Cp)2LuH]2>[(Me5Cp) 2SmH]2>[(Me5Cp)2LaH]2.

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