The cationic isomerization polymerization of bicyclo[2.2.1]hepta-2,5-diene (norbornadiene) was investigated. The synthesis of gel-free poly(3,5-tricyclo[2.2.1.0(2,6)]heptylene) was achieved at a reaction temperature of 0 degrees C. These polymerizations were initiated by AlCl3 in the presence of the weakly donating additives nitrobenzene or nitromethane. NMR spectra show that the polymer contains a small fraction (between 2 and 4 mol-%) of branched structures in addition to a small amount of 5,7-linked bicyclic olefin units (approximately 2%). A reaction mechanism involving non-classical carbocation intermediates is proposed in order to account for the 5,7-enchainment of the bicycloheptenylene units, which contrasts with earlier studies on cationic norbornadiene polymerizations. Further, pentamethylbenzene was utilized as a chain transfer reagent in order to adjust the number average molecular weight (M) over bar(n) to values below 2500.

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ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPolymers Composed of Triangular Repeating Units. Pd2+-Catalyzed Addition Polymerizations of 3,3-DialkylcyclopropenesStephen Rush, Annette Reinmuth, Wilhelm Risse, John O'Brien, Dino R. Ferro, and Incoronata TrittoView Author Information Department of Chemistry, University College Dublin Belfield, Dublin 4, Ireland Department of Chemistry, University of Dublin Trinity College, Dublin 2, Ireland Istituto di Chimica delle Macromolecole del CNR Milano Via E. Bassini 15, 20133 Milano, ItalyCite this: J. Am. Chem. Soc. 1996, 118, 48, 12230–12231Publication Date (Web):December 4, 1996Publication History Received11 April 1996Published online4 December 1996Published inissue 1 January 1996https://pubs.acs.org/doi/10.1021/ja961192uhttps://doi.org/10.1021/ja961192urapid-communicationACS PublicationsCopyright © 1996 American Chemical SocietyRequest reuse permissionsArticle Views548Altmetric-Citations39LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Catalysts,Ligands,Monomers,Polymerization,Polymers Get e-Alerts

Homo- and copolymers containing repeating units based on bicyclo[2.2.1]hept-5-en-2-ylmethyl decanoate(endo/exo ratio= 80/20), bicyclo[2.2.1]hept-5-ene-2-carboxylic acid methyl ester (exo/endo= 80/20), bicyclo[2.2.1]hept-5-ene-2-methanol (endo/exo= 80/20) and bicyclo[2.2.1]hept-5-ene-2-carboxylic acid (100% endp) were prepared in 49-99% yields with {(η 3 -allyl)Pd(BF 4 )} and {(η 3 -allyl)Pd(SbF 6 )} as catalysts. The catalyst containing the hexafluoroantimonate ion was slightly more active than the tetrafluoroborate-based Pd complex

Cationic Pd(II)-complexes with weakly coordinating ligands were used for the olefin addition polymerization of strained polycyclic olefins. The cyclic structure of the monomers remained intact during the reaction which contrasts with products obtained from the olefin metathesis polymerization. The Pd(II)-catalyzed polymerizations showed the features of a ''living'' polymerization, when norbornene and selected exo-substituted norbornene derivatives were used as the monomers. Endo- and exo-dicyclopentadiene, exo-1,2-dihydrodicyclopentadiene, endo,exo-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene and endo,exo-1,4,5,8-dimethano-1,4,4,a,5,8,8 naphthalene were converted into the corresponding rigid polymers. The exo-substituted monomers were found to polymerize at a higher rate than the corresponding or similar endo-substituted monomers. The polymerization of norbornadiene and the subsequent thermal elimination of cyclopentadiene resulted in the formation of polyacetylene.

Fluoroalkyl-substituted bicyclic and tricyclic olefins were polymerized by ring-opening olefin metathesis polymerization (ROMP). The monomers used were mixtures of exo- and endo-isomers of 5,6,6-trifluoro-6-(trifluoromethyl)spiro(bicyclo[2.2.l]hept-2-ene-7,1'-cyclopropane), 5,6-difluoro-5-(trifluoromethyl)-6-(heptafluoroisopropyl)bicyclo[2.2.1]hept-2-ene, and 2,3,3,4,4,5,5,6-octafluorotricyclo[2.2.1]hept-2-ene obtained by the Diels-Alder reaction of cyclopentadiene and spiro[2.4]hepta-4,6-diene with perfluorinated olefins. The polymerization reactions were carried out with a conventional catalyst based on tungsten hexachloride. The exo-isomers were found to be more reactive than the corresponding endo-isomers. This difference in reactivity was larger for monomers containing more voluminous substituents. A model based on steric repulsion is proposed to describe the selectivity for polymerization of the exo-isomers.

Spiro(bicyclo[2.2.1]hept-2-ene-7,1'-cyclopropane) was polymerized by ring-opening olefin metathesis polymerization (ROMP) to produce poly[2,1'-spirocyclopropane-1,3-cyclopentylenevinylene]. The polymerization reactions were carried out with conventional metathesis catalysts based on W and Ru. The steric bulk of the three-membered ring was not sufficient to prevent the approach of the catalytically active transition metal carbene species to the exo face of the monomer. However, steric hindrance had an important influence on the microstructure of the polymers formed. The resulting polymers contained a high proportion of trans carbon-carbon double bonds and a slight excess of racemic dyads. Models based on steric repulsion are proposed to describe trans cis and racemic, meso selectivity. Hydrogenation of the double bonds resulted in the formation of partially crystalline poly[2,1'-spirocyclopropane-1,3-cyclopentyleneethylene].

Die Makromolekulare Chemie, Rapid CommunicationsVolume 13, Issue 10 p. 455-459 Article Pd(II)-catalyzed polymerization of norbornene derivatives Christof Mehler, Christof Mehler Philipps Universität Marburg, Fachbereich Physikalische Chemie — Polymere, Hans Meerweinstr., 3550 Marburg, GermanySearch for more papers by this authorWilhelm Risse, Corresponding Author Wilhelm Risse University College Dublin, Department of Chemistry, Belfield, Dublin 4, IrelandUniversity College Dublin, Department of Chemistry, Belfield, Dublin 4, IrelandSearch for more papers by this author Christof Mehler, Christof Mehler Philipps Universität Marburg, Fachbereich Physikalische Chemie — Polymere, Hans Meerweinstr., 3550 Marburg, GermanySearch for more papers by this authorWilhelm Risse, Corresponding Author Wilhelm Risse University College Dublin, Department of Chemistry, Belfield, Dublin 4, IrelandUniversity College Dublin, Department of Chemistry, Belfield, Dublin 4, IrelandSearch for more papers by this author First published: October 1992 https://doi.org/10.1002/marc.1992.030131003Citations: 29AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume13, Issue10October 1992Pages 455-459 RelatedInformation

Cationic Pd2+ complexes were used for the preparation of poly(2,3-bicyclo[2.2.1] hept-2-ene), a saturated polymer with the bicyclic structure of the monomer left intact. The polymer was characterized by thermal analyses and molecular weight determinations. Samples with narrow molecular weight distributions (polydispersities Mw/Mn, as low as 1.07) were prepared with the initiator [Pd(CH3CN)4][BF4]2. Polymer chain growth of this addition polymer was found to continue after renewed monomer addition, indicating rare chain transfer and chain termination.

Ring-opening olefin metathesis polymerization (ROMP) of partially fluorinated norbornene derivatives with a catalyst based on WCl6 gave amorphous poly(1,3-cyclopentenylene vinylene) derivatives with high glass transition temperatures, low indices of refraction and good oxidative and thermal stability. The influence of the substitution pattern on monomer reactivities and polymer properties was investigated. Exo-substituted monomers were found to be more reactive than the corresponding endo isomers.

Norbornene derivatives containing ester substituents were submitted to Pd(II)-catalyzed vinyl addition polymerization. The transition metal catalyst was found to tolerate the ester functionality. However, the rate of polymerization was reduced in comparison to the polymerization of norbornene. The polymerization of the pure exo-isomers produced substantially higher yields than reactions of monomers containing a high proportion of the corresponding endo-isomer. By varying the ester substituent, amorphous polymers with glass transition temperatures over the range of -40 to 268-degrees-C were synthesized. An approximately linear relationship of molecular weight-to monomer conversion was established, and the non-uniformity remained narrow (M(w)BAR/M(n)BAR almost-equal-to 1,15-1,25) until high conversions for several of the exo-isomers studied. This indicates that both chain transfer and chain termination are rare.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAddition polymerization of norbornene catalyzed by palladium(2+) compounds. A polymerization reaction with rare chain transfer and chain terminationChristof Mehler and Wilhelm RisseCite this: Macromolecules 1992, 25, 16, 4226–4228Publication Date (Print):August 1, 1992Publication History Published online1 May 2002Published inissue 1 August 1992https://pubs.acs.org/doi/10.1021/ma00042a030https://doi.org/10.1021/ma00042a030research-articleACS PublicationsRequest reuse permissionsArticle Views629Altmetric-Citations113LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The present article reviews the development of well-defined transition metal compounds which catalyze the ring-opening polymerization of strained cyclic olefins by the olefin metathesis reaction (ROMP). Several titana- and tantalacyclobutane compounds and tungsten- and molybdenum carbenes polymerize norbornene and norbornene derivatives by a "living" mechanisms, thus producing polymers of controlled molecular weights with narrow molecular weight distributions. Some of these systems have been successfully applied to the synthesis of block and graft copolymers. Studies on Ru-based catalysts resulted in the development of olefin metathesis polymerizations in aqueous solutions.

Die Makromolekulare Chemie, Rapid CommunicationsVolume 12, Issue 2 p. 107-112 Article Ring-opening olefin metathesis polymerization of fluoroalkyl-substituted polycyclic olefins† Norbert Seehof, Norbert Seehof Philipps Universität Marburg, Fachbereich Physikalische Chemie—Polymere, Hans Meerwein Str., 3550 Marburg, F.R.G.Search for more papers by this authorWilhelm Risse, Corresponding Author Wilhelm Risse Philipps Universität Marburg, Fachbereich Physikalische Chemie—Polymere, Hans Meerwein Str., 3550 Marburg, F.R.G.Philipps Universität Marburg, Fachbereich Physikalische Chemie—Polymere, Hans Meerwein Str., 3550 Marburg, F.R.G.Search for more papers by this author Norbert Seehof, Norbert Seehof Philipps Universität Marburg, Fachbereich Physikalische Chemie—Polymere, Hans Meerwein Str., 3550 Marburg, F.R.G.Search for more papers by this authorWilhelm Risse, Corresponding Author Wilhelm Risse Philipps Universität Marburg, Fachbereich Physikalische Chemie—Polymere, Hans Meerwein Str., 3550 Marburg, F.R.G.Philipps Universität Marburg, Fachbereich Physikalische Chemie—Polymere, Hans Meerwein Str., 3550 Marburg, F.R.G.Search for more papers by this author First published: February 1991 https://doi.org/10.1002/marc.1991.030120207Citations: 8 † Published later at the request of the authors. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume12, Issue2February 1991Pages 107-112 RelatedInformation