Carbon K-Edge X-ray Absorption Spectroscopy and Time-Dependent Density Functional Theory Examination of Metal–Carbon Bonding in Metallocene Dichlorides.
Metal–carbon covalence in (CH)MCl (M = Ti, Zr, Hf) has been evaluated using carbon K-edge X-ray absorption spectroscopy (XAS) as well as ground-state and time-dependent hybrid density functional theory (DFT and TDDFT). Differences in orbital mixing were determined experimentally using transmission X...
| Publicado en: | Journal of the American Chemical Society Vol. 135; no. 39; pp. 14731 - 14741 |
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| Autores principales: | , , , , , , , , |
| Formato: | Artículo |
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American Chemical Society
10/2/2013
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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=90641325&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 90641325 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: 10/2/2013 vid: 135 iid: 39 pid: 997 pub: American Chemical Society artinfo: ui: 90641325 10.1021/ja405844j ppf: 14731 ppct: 10 formats: tig: atl: Carbon K-Edge X-ray Absorption Spectroscopy and Time-Dependent Density Functional Theory Examination of Metal–Carbon Bonding in Metallocene Dichlorides. aug: au: Minasian, Stefan G. Keith, Jason M. Batista, Enrique R. Boland, Kevin S. Kozimor, Stosh A. Martin, Richard L. Shuh, David K. Tyliszczak, Tolek Vernon, Louis J. affil: Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States su: Carbon Group 14 elements X-ray absorption Electromagnetic wave absorption Time-dependent density functional theory sug: subj: Carbon Group 14 elements X-ray absorption Electromagnetic wave absorption Time-dependent density functional theory ab: Metal–carbon covalence in (CH)MCl (M = Ti, Zr, Hf) has been evaluated using carbon K-edge X-ray absorption spectroscopy (XAS) as well as ground-state and time-dependent hybrid density functional theory (DFT and TDDFT). Differences in orbital mixing were determined experimentally using transmission XAS of thin crystalline material with a scanning transmission X-ray microscope (STXM). Moving down the periodic table (Ti to Hf) has a marked effect on the experimental transition intensities associated with the low-lying antibonding 1a* and 1b* orbitals. The peak intensities, which are directly related to the M–(CH) orbital mixing coefficients, increase from 0.08(1) and 0.26(3) for (CH)TiCl to 0.31(3) and 0.75(8) for (CH)ZrCl, and finally to 0.54(5) and 0.83(8) for (CH)HfCl. The experimental trend toward increased peak intensity for transitions associated with 1a* and 1b* orbitals agrees with the calculated TDDFT oscillator strengths [0.10 and 0.21, (CH)TiCl; 0.21 and 0.73, (CH)ZrCl; 0.35 and 0.69, (CH)HfCl] and with the amount of C 2p character obtained from the Mulliken populations for the antibonding 1a* and 1b* orbitals [8.2 and 23.4%, (CH)TiCl; 15.3 and 39.7%, (CH)ZrCl; 20.1 and 50.9%, (CH)HfCl]. The excellent agreement between experiment, theory, and recent Cl K-edge XAS and DFT measurements shows that C 2p orbital mixing is enhanced for the diffuse Hf (5d) and Zr (4d) atomic orbitals in relation to the more localized Ti (3d) orbitals. These results provide insight into how changes in M–Cl orbital mixing within the metallocene wedge are correlated with periodic trends in covalent bonding between the metal and the cyclopentadienide ancillary ligands. 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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