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Norbornene

About: Norbornene is a research topic. Over the lifetime, 5628 publications have been published within this topic receiving 104495 citations. The topic is also known as: norbornylene & norcamphene.


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Journal ArticleDOI
TL;DR: In this paper, the microstructural analysis by 13C NMR of alternating isotactic copolymers was completely obtained at pentad level by a methodology that exploits all the peak areas of the spectra and accounts for the stochastic requirements of the copolymer chain.
Abstract: The copolymerization of ethylene and norbornene by catalytic systems composed of i-Pr[(3-R−Cp)(Flu)]ZrCl2 (R = Me or Pri) and methylaluminoxane was investigated. Isotactic, alternating ethylene−norbornene (E−N) copolymers with percentages of pentads NENEN up to 21% and norbornene incorporation up to 40% were obtained. NEENE sequences were observed in copolymers synthesized with both metallocenes. The microstructural analysis by 13C NMR of such alternating isotactic copolymers was completely obtained at pentad level by a methodology that exploits all the peak areas of the spectra and accounts for the stoichoimetric requirements of the copolymer chain. Such a methodology has allowed us to reconsider some controversial assignments of ethylene CH2 signals. The present understanding of E−N copolymer NMR spectra at the pentad level has allowed us to test the statistical model best describing E−N copolymerization with C1 symmetric catalysts and to study the influence of ligand substitution of these catalysts on ...

48 citations

Journal ArticleDOI
TL;DR: In this article, the steric hindrance has significant effects on their catalytic activities for polymerization of norbornene, and the results showed that steric interference has a significant effect on the catalytic activity of the bis-[ N -substituted methyl]-salicylideneiminato]nickel/MAO complex.
Abstract: The bis-[ N -(substituted methyl)-salicylideneiminato]nickel/MAO systems were utilized to promote the vinylic homo-polymerization of norbornene. The results displayed that steric hindrance has significant effects on their catalytic activities for polymerization of norbornene. The complex a , bis-[ N -(diphenylmethyl)-salicylideneiminato]nickel, is systematically investigated with the catalytic activity up to 4.23×10 8 g PNB/(mol Ni h) and the average molecular weight up to 3.26×10 6 g/mol. All the polymer samples obtained here are soluble at room temperature in chlorobenzene. No indication of stereoregularity was observed; this was verified by the amorphous morphology of the products. The catalytic activities, yields, molecular weights and molecular weight distributions could be controlled over a wide range via variations of the reaction parameters.

48 citations

Journal ArticleDOI
TL;DR: The spectra of the endo- and exo-cyclopropano-norbornene were analyzed in this article, and it was shown that a significant homoconjugation exists between the π-orbital of the double bond and the symmetric Walsh-esorbital in the cyclopropane ring in the exoisomer.
Abstract: Photoelectron spectra of endo- and exo-cyclopropano-norbornene ( = endo- and exo-tricyclo[3.2.1.02.4]octa-6-ene) show that a significant homoconjugation exists between the π-orbital of the double bond and the symmetric Walsh-es-orbital of the cyclopropane ring in the exo-isomer, whereas the interaction is negligeable in the endo-derivative.

48 citations

Journal ArticleDOI
TL;DR: In this article, a ring opening metathesis polymerization (ROMP) of norbomene was achieved using a new Ru(ID-vinylidene complex as catalyst precursor.

48 citations

Journal ArticleDOI
TL;DR: In this article, the precursors for ring opening metathesis polymerization (ROMP) were evaluated and the X-ray structure of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand was determined.
Abstract: N-Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC-η6-arene ligand have been prepared and evaluated as precursors for ring opening metathesis polymerization (ROMP). The reaction of [RuCl2(p-cymene)]2 with electron-rich olefins of the bis(imidazolinylidene) type containing at least one arylmethyl-N chain (aryl: 2,4,6-trimethylphenyl, 3,4,5-trimethoxyphenyl) selectively leads, upon heating, to ruthenium(II) complexes 2 containing a chelating bridged carbene η6-arene ligand. The reaction of complexes containing an additional ROCH2CH2N group with AgOTf leads to ionic complexes 5 with a tridentate trifunctional carbene/arene/ether ligand. The X-ray structure of[RuCl2{η1-CN(CH2{η6-C6H2Me3-2,4,6})CH2CH2N(CH2{C6H2(OMe)3-3,4,5})}] (2c) and that of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand that provides ten electrons, [RuCl{η1-CN(CH2{η6-C6H2Me3-2,4,6})CH2CH2N(CH2CH2OCH3)}][CF3SO3] (5e), have been determined. The precursors 2 in the presence of AgOTf and propargyl alcohol, in order to produce an allenylidene initiator, and complexes 5 in the presence of propargyl alcohol lead to ROMP of norbornene. It is shown that initial chloride abstraction is required and that the catalyst activity is increased by using mesityl–ruthenium precursors and coordinated branched ether complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

48 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202376
2022165
2021113
2020119
2019141
2018136