An Anion-Dependent Switch in Selectivity Results from a Change of C--H Activation Mechanism in the Reaction of an lmidazolium Salt with lrH(PPh).
Changing the counteranion along the series Br, BF, PF, SbF in their ion-paired 2-pyridylmethyl imidazolium salts causes the kinetic reaction products with lrH(PPh) to switch from chelating N-heterocyclic carbenes (NHCs) having normal C2 (N path) to abnormal C5 binding (AN path). Computational work (...
| Publicado en: | Journal of the American Chemical Society Vol. 127; no. 46; pp. 16299 - 16312 |
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| Autores principales: | , , , , , , , , |
| Formato: | Artículo |
| Publicado: |
American Chemical Society
11/23/2005
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=19296907&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 19296907 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 11/23/2005 vid: 127 iid: 46 pid: 997 pub: American Chemical Society artinfo: ui: 19296907 10.1021/ja055317j ppf: 16299 ppct: 13 formats: tig: atl: An Anion-Dependent Switch in Selectivity Results from a Change of C--H Activation Mechanism in the Reaction of an lmidazolium Salt with lrH(PPh). aug: au: Appelhans, Leah N. Zuccaccia, Daniele Kovacevic, Anes Chianese, Anthony R. Miecznikowski, John R. Macchioni, Alceo Ciot, Eric Eisenstein, Odile Crabtree, Robert H. affil: Department of Chemistry, 225 Prospect Street, Yale University, New Haven, Connecticut 06520-8107. Dipartimento di Chimica, Università di Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy. LSDSMS (UMR 5636 CNRS), cc 14, Institut Gerhardt, Université Montpellier 2, F-34095 Montpellier Cedex 5, France. su: Salts Anions Density functionals Carbenes Proton transfer reactions Nuclear magnetic resonance spectroscopy Activation (Chemistry) sug: subj: Salts Anions Density functionals Carbenes Proton transfer reactions Nuclear magnetic resonance spectroscopy Activation (Chemistry) ab: Changing the counteranion along the series Br, BF, PF, SbF in their ion-paired 2-pyridylmethyl imidazolium salts causes the kinetic reaction products with lrH(PPh) to switch from chelating N-heterocyclic carbenes (NHCs) having normal C2 (N path) to abnormal C5 binding (AN path). Computational work (DFT) suggests that the AN path involves C-H oxidative addition to lr to give Ir with little anion dependence. The N path, in contrast, goes by heterolytic C-H activation with proton transfer to the adjacent hydride. The proton that is transferred is accompanied by the counteranion in an anion-coupled proton transfer, leading to an anion dependence of the N path, and therefore of the N/AN selectivity. The N path goes via Ir, not lr, because the normal NHC is a much less strong donor ligand than the abnormal NHC. PGSE NMR experiments support the formation of ion-pair in both the reactants and the products. F,¹H-HOESY NMR experiments indicate an ion-pair structure for the products that is consistent with the computational prediction (ONIOM(B3PW91/UFF)). pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2005 holdings: @attributes: islocal: N |
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