Isolation of a Mixed Valence Diiron Hydride: Evidence for a Spectator Hydride in Hydrogen Evolution Catalysis.
The mixed-valence diiron hydrido complex (μ-H)Fe(pdt)(CO)(dppv) ([H1], where pdt =1,3-propanedithiolate and dppv = cis-1,2-CH(PPh)), was generated by reduction of the differous hydride [H1] using decamethylcobaltocene. Crystallographic analysis shows that [H1] retains the stereochemistry of its prec...
| Publicado en: | Journal of the American Chemical Society Vol. 135; no. 9; pp. 3633 - 3640 |
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| Autores principales: | , , , |
| Formato: | Artículo |
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American Chemical Society
3/6/2013
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| 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=86880150&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 86880150 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: 3/6/2013 vid: 135 iid: 9 pid: 997 pub: American Chemical Society artinfo: ui: 86880150 10.1021/ja312458f ppf: 3633 ppct: 7 formats: tig: atl: Isolation of a Mixed Valence Diiron Hydride: Evidence for a Spectator Hydride in Hydrogen Evolution Catalysis. aug: au: Wenguang Wang Nilges, Mark J. Rauchfuss, Thomas B. Stein, Matthias affil: School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801, United States Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany su: Phosphorus compounds Density functionals Spectrum analysis Hydrogen analysis Stereochemistry sug: subj: Phosphorus compounds Density functionals Spectrum analysis Hydrogen analysis Stereochemistry ab: The mixed-valence diiron hydrido complex (μ-H)Fe(pdt)(CO)(dppv) ([H1], where pdt =1,3-propanedithiolate and dppv = cis-1,2-CH(PPh)), was generated by reduction of the differous hydride [H1] using decamethylcobaltocene. Crystallographic analysis shows that [H1] retains the stereochemistry of its precursor, where one dppv ligand spans two basal sites and the other spans apical and basal positions. The Fe---Fe bond elongates to 2.80 from 2.66 Å, but the Fe-P bonds only change subtly. Although the Fe-H distances are indistinguishable in the precursor, they differ by 0.2 Å in [H1]. The X-band electron paramagnetic resonance (EPR) spectrum reveals the presence of two stereoisomers, the one characterized crystallographically and a contribution of about 10% from a second symmetrical (sym) isomer wherein both dppv ligands occupy apical-basal sites. The unsymmetrical (unsym) arrangement of the dppv ligands is reflected in the values of A(P), which range from 31 MHz for the basal phosphines to 284 MHz for the apical phosphine. Density functional theory calculations were employed to rationalize the electronic structure of [H1] and to facilitate spectral simulation and assignment of EPR parameters including H and P hyperfine couplings. The EPR spectra of [H1] and [D1] demonstrate that the singly occupied molecular orbital is primarily localized on the Fe center with the longer bond to H, that is, Fe-H···Fe. The coupling to the hydride is A(H) = 55 and 74 MHz for unsym- amd sym-[H1], respectively. Treatment of [H1] with H gives 0.5 equiv of H and [H1]. Reduction of D affords D, leaving the hydride ligand intact. These experiments demonstrate that the bridging hydride ligand in this complex is a spectator in the hydrogen evolution reaction. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2013 holdings: @attributes: islocal: N |
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