Computational Study of the Reaction of CF with [IrMe(PEt)]: Identification of a Phosphine-Assisted C—F Activation Pathway via a Metallophosphorane Intermediate.
Density functional theory calculations have been used to model the reaction of CF with [IrMe(PEt)], which proceeds with both C-F and P-C bond activation to yield trans-[Ir(CF)(PEt)(PEtF)], CH, and CH (Blum, O.; Frolow, F.; Milstein, D. J. Chem. Soc., Chem. Commun. 1991, 258). Using a model species,...
| Published in: | Journal of the American Chemical Society Vol. 130; no. 46; pp. 15490 - 15499 |
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| Main Authors: | , |
| Format: | Article |
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American Chemical Society
11/19/2008
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| Online Access: | View this record in EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=35398154&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 35398154 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: 11/19/2008 vid: 130 iid: 46 pid: 997 pub: American Chemical Society artinfo: ui: 35398154 10.1021/ja804622j ppf: 15490 ppct: 9 formats: tig: atl: Computational Study of the Reaction of CF with [IrMe(PEt)]: Identification of a Phosphine-Assisted C—F Activation Pathway via a Metallophosphorane Intermediate. aug: au: Erhardt, Stefan Macgregor, Stuart A. affil: School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EHJ4 4AS, U.K. su: Chemical reactions Calcium fluoride Phosphine Density functionals Ligands (Chemistry) Charge exchange sug: subj: Chemical reactions Calcium fluoride Phosphine Density functionals Ligands (Chemistry) Charge exchange ab: Density functional theory calculations have been used to model the reaction of CF with [IrMe(PEt)], which proceeds with both C-F and P-C bond activation to yield trans-[Ir(CF)(PEt)(PEtF)], CH, and CH (Blum, O.; Frolow, F.; Milstein, D. J. Chem. Soc., Chem. Commun. 1991, 258). Using a model species, trans-[IrMe(PH)(PHEt)], a low-energy mechanism involving nucleophilic attack of the electron-rich Ir metal center at CF with displacement of fluoride has been identified. A novel feature of this process is the capture of fluoride by a phosphine ligand to generate a metallophosphorane intermediate [Ir(CF)(Me)(PH)(PHEtF)]. These events occur in a single step via a 4-centered transition state, in a process that we have termed "phosphine-assisted C-F activation". Alternative mechanisms based on C-F activation via concerted oxidative addition or electron-transfer processes proved less favorable. From the metallophosphorane intermediate the formation of the final products can be accounted for by facile ethyl group transfer from phosphorus to iridium followed by β-H elimination of ethene and reductive elimination of methane. The interpretation of phosphine-assisted C-F activation in terms of nucleophilic attack is supported by the reduced activation barriers computed with the more electron-rich model reactant trans- [IrMe(PMe)(PMeEt)] and the higher barriers found with lesser fluorinated arenes. Reactivity patterns for a range of fluoroarenes indicate the dominance of the presence of ortho-F substituents in promoting phosphine-assisted C-F activation, and an analysis of the charge distribution and transition state geometries indicates that this process is controlled by the strength of the Ir-aryl bond that is being formed. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2008 holdings: @attributes: islocal: N |
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