Abstract
This contribution describes the implementation of the binuclear organotitanium "constrained geometry catalysts" (CGCs), (μ-CH 2CH2-3,3′){(η5-indenyl)[1-Me 2Si(tBuN)](TiMe2)}2[EBICGC(TiMe 2)2; Ti2] and (μ-CH2-3,3′) {(η5-indenyl)[1-Me2Si(tBuN)](TiMe 2)}2[MBICGC(TiMe2)2; C1-Ti 2], in combination with the bifunctional bisborane activator 1,4-(C6F5)2BC6F4B(C 6F5)2 (BN2) in ethylene + olefin copolymerization processes. Specifically examined are the classically poorly responsive 1,1-disubstituted comonomers, methylenecyclopentane (C), methylenecyclohexane (D), 1,1,2-trisubstituted 2-methyl-2-butene (E), and isobutene (F). For the first three comonomers, this represents the first report of their incorporation into a polyethylene backbone via a coordination polymerization process. C and D are incorporated via a ring-unopened pathway, and E is incorporated via a novel pathway involving 2-methyl-1 -butene enchainment in the copolymer backbone. In ethylene copolymerization, Ti 2 + BN2 enchains ∼2.5 times more C, ∼2.5 times more D, and ∼2.3 times more E than the mononuclear catalyst analogue [1-Me2Si(3-ethylindenyl)-(tBuN)]TiMe2 (Ti 1) + B(C6F5)3 (BN) under identical polymerization conditions. Polar solvents are found to weaken the catalyst-cocatalyst ion pairing, thus influencing the comonomer enchainment selectivity.
| Original language | English |
|---|---|
| Pages (from-to) | 14756-14768 |
| Number of pages | 13 |
| Journal | Journal of the American Chemical Society |
| Volume | 127 |
| Issue number | 42 |
| DOIs | |
| Publication status | Published - Nov 1 2005 |
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- Chemistry(all)
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Coordination copolymerization of severely encumbered isoalkenes with ethylene : Enhanced enchainment mediated by binuclear catalysts and cocatalysts. / Li, Hongbo; Li, Liting; Schwartz, David J.; Metz, Matthew V.; Marks, Tobin J; Liable-Sands, Louise; Rheingold, Arnold L.
In: Journal of the American Chemical Society, Vol. 127, No. 42, 01.11.2005, p. 14756-14768.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Coordination copolymerization of severely encumbered isoalkenes with ethylene
T2 - Enhanced enchainment mediated by binuclear catalysts and cocatalysts
AU - Li, Hongbo
AU - Li, Liting
AU - Schwartz, David J.
AU - Metz, Matthew V.
AU - Marks, Tobin J
AU - Liable-Sands, Louise
AU - Rheingold, Arnold L.
PY - 2005/11/1
Y1 - 2005/11/1
N2 - This contribution describes the implementation of the binuclear organotitanium "constrained geometry catalysts" (CGCs), (μ-CH 2CH2-3,3′){(η5-indenyl)[1-Me 2Si(tBuN)](TiMe2)}2[EBICGC(TiMe 2)2; Ti2] and (μ-CH2-3,3′) {(η5-indenyl)[1-Me2Si(tBuN)](TiMe 2)}2[MBICGC(TiMe2)2; C1-Ti 2], in combination with the bifunctional bisborane activator 1,4-(C6F5)2BC6F4B(C 6F5)2 (BN2) in ethylene + olefin copolymerization processes. Specifically examined are the classically poorly responsive 1,1-disubstituted comonomers, methylenecyclopentane (C), methylenecyclohexane (D), 1,1,2-trisubstituted 2-methyl-2-butene (E), and isobutene (F). For the first three comonomers, this represents the first report of their incorporation into a polyethylene backbone via a coordination polymerization process. C and D are incorporated via a ring-unopened pathway, and E is incorporated via a novel pathway involving 2-methyl-1 -butene enchainment in the copolymer backbone. In ethylene copolymerization, Ti 2 + BN2 enchains ∼2.5 times more C, ∼2.5 times more D, and ∼2.3 times more E than the mononuclear catalyst analogue [1-Me2Si(3-ethylindenyl)-(tBuN)]TiMe2 (Ti 1) + B(C6F5)3 (BN) under identical polymerization conditions. Polar solvents are found to weaken the catalyst-cocatalyst ion pairing, thus influencing the comonomer enchainment selectivity.
AB - This contribution describes the implementation of the binuclear organotitanium "constrained geometry catalysts" (CGCs), (μ-CH 2CH2-3,3′){(η5-indenyl)[1-Me 2Si(tBuN)](TiMe2)}2[EBICGC(TiMe 2)2; Ti2] and (μ-CH2-3,3′) {(η5-indenyl)[1-Me2Si(tBuN)](TiMe 2)}2[MBICGC(TiMe2)2; C1-Ti 2], in combination with the bifunctional bisborane activator 1,4-(C6F5)2BC6F4B(C 6F5)2 (BN2) in ethylene + olefin copolymerization processes. Specifically examined are the classically poorly responsive 1,1-disubstituted comonomers, methylenecyclopentane (C), methylenecyclohexane (D), 1,1,2-trisubstituted 2-methyl-2-butene (E), and isobutene (F). For the first three comonomers, this represents the first report of their incorporation into a polyethylene backbone via a coordination polymerization process. C and D are incorporated via a ring-unopened pathway, and E is incorporated via a novel pathway involving 2-methyl-1 -butene enchainment in the copolymer backbone. In ethylene copolymerization, Ti 2 + BN2 enchains ∼2.5 times more C, ∼2.5 times more D, and ∼2.3 times more E than the mononuclear catalyst analogue [1-Me2Si(3-ethylindenyl)-(tBuN)]TiMe2 (Ti 1) + B(C6F5)3 (BN) under identical polymerization conditions. Polar solvents are found to weaken the catalyst-cocatalyst ion pairing, thus influencing the comonomer enchainment selectivity.
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U2 - 10.1021/ja052995x
DO - 10.1021/ja052995x
M3 - Article
VL - 127
SP - 14756
EP - 14768
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 42
ER -