dc.contributor.author | Engel, Julien | |
dc.contributor.author | Smit, Wietse | |
dc.contributor.author | Foscato, Marco | |
dc.contributor.author | Occhipinti, Giovanni | |
dc.contributor.author | Törnroos, Karl Wilhelm | |
dc.contributor.author | Jensen, Vidar Remi | |
dc.date.accessioned | 2018-08-17T12:15:26Z | |
dc.date.available | 2018-08-17T12:15:26Z | |
dc.date.issued | 2017 | |
dc.Published | Engel 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):16609-16619 | eng |
dc.identifier.issn | 1520-5126 | en_US |
dc.identifier.issn | 0002-7863 | en_US |
dc.identifier.uri | https://hdl.handle.net/1956/18137 | |
dc.description.abstract | Ruthenium-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.iso | eng | eng |
dc.publisher | American Chemical Society | en_US |
dc.rights | Attribution CC BY | eng |
dc.rights.uri | http://creativecommons.org/licenses/by/4.0 | eng |
dc.title | Loss and Reformation of Ruthenium Alkylidene: Connecting Olefin Metathesis, Catalyst Deactivation, Regeneration, and Isomerization | en_US |
dc.type | Peer reviewed | |
dc.type | Journal article | |
dc.date.updated | 2018-03-07T14:05:43Z | |
dc.description.version | publishedVersion | en_US |
dc.rights.holder | Copyright 2017 American Chemical Society | en_US |
dc.identifier.doi | https://doi.org/10.1021/jacs.7b07694 | |
dc.identifier.cristin | 1545963 | |
dc.source.journal | Journal of the American Chemical Society | |
dc.relation.project | Norges forskningsråd: 203379 | |
dc.relation.project | Norges forskningsråd: 239288 | |
dc.relation.project | Norges forskningsråd: 262370 | |
dc.relation.project | Norges forskningsråd: 208335 | |
dc.relation.project | Notur/NorStore: NS2506K | |
dc.relation.project | Notur/NorStore: NN2506K | |