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dc.contributor.authorEngel, Julien
dc.contributor.authorSmit, Wietse
dc.contributor.authorFoscato, Marco
dc.contributor.authorOcchipinti, Giovanni
dc.contributor.authorTörnroos, Karl Wilhelm
dc.contributor.authorJensen, Vidar Remi
dc.date.accessioned2018-08-17T12:15:26Z
dc.date.available2018-08-17T12:15:26Z
dc.date.issued2017
dc.PublishedEngel J, Smit W, Foscato M, Occhipinti G, Törnroos KW, Jensen VR. Loss and Reformation of Ruthenium Alkylidene: Connecting Olefin Metathesis, Catalyst Deactivation, Regeneration, and Isomerization. Journal of the American Chemical Society. 2017;139(46):16609-16619eng
dc.identifier.issn1520-5126en_US
dc.identifier.issn0002-7863en_US
dc.identifier.urihttps://hdl.handle.net/1956/18137
dc.description.abstractRuthenium-based olefin metathesis catalysts are used in laboratory-scale organic synthesis across chemistry, largely thanks to their ease of handling and functional group tolerance. In spite of this robustness, these catalysts readily decompose, via little-understood pathways, to species that promote double-bond migration (isomerization) in both the 1-alkene reagents and the internal-alkene products. We have studied, using density functional theory (DFT), the reactivity of the Hoveyda–Grubbs second-generation catalyst 2 with allylbenzene, and discovered a facile new decomposition pathway. In this pathway, the alkylidene ligand is lost, via ring expansion of the metallacyclobutane intermediate, leading to the spin-triplet 12-electron complex (SIMes)RuCl2 (3R21, SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene). DFT calculations predict 3R21 to be a very active alkene isomerization initiator, either operating as a catalyst itself, via a η3-allyl mechanism, or, after spin inversion to give R21 and formation of a cyclometalated Ru-hydride complex, via a hydride mechanism. The calculations also suggest that the alkylidene-free ruthenium complexes may regenerate alkylidene via dinuclear ruthenium activation of alkene. The predicted capacity to initiate isomerization is confirmed in catalytic tests using p-cymene-stabilized R21 (5), which promotes isomerization in particular under conditions favoring dissociation of p-cymene and disfavoring formation of aggregates of 5. The same qualitative trends in the relative metathesis and isomerization selectivities are observed in identical tests of 2, indicating that 5 and 2 share the same catalytic cycles for both metathesis and isomerization, consistent with the calculated reaction network covering metathesis, alkylidene loss, isomerization, and alkylidene regeneration.en_US
dc.language.isoengeng
dc.publisherAmerican Chemical Societyen_US
dc.rightsAttribution CC BYeng
dc.rights.urihttp://creativecommons.org/licenses/by/4.0eng
dc.titleLoss and Reformation of Ruthenium Alkylidene: Connecting Olefin Metathesis, Catalyst Deactivation, Regeneration, and Isomerizationen_US
dc.typePeer reviewed
dc.typeJournal article
dc.date.updated2018-03-07T14:05:43Z
dc.description.versionpublishedVersionen_US
dc.rights.holderCopyright 2017 American Chemical Societyen_US
dc.identifier.doihttps://doi.org/10.1021/jacs.7b07694
dc.identifier.cristin1545963
dc.source.journalJournal of the American Chemical Society
dc.relation.projectNorges forskningsråd: 203379
dc.relation.projectNorges forskningsråd: 239288
dc.relation.projectNorges forskningsråd: 262370
dc.relation.projectNorges forskningsråd: 208335
dc.relation.projectNotur/NorStore: NS2506K
dc.relation.projectNotur/NorStore: NN2506K


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