On the Origin of Alternating Bond Distortions and the Emergence of Chirality in Polyoxometalate Anions.
Alternating short and long bond length (ABL) distortions observed within the ring structures of molecular metal oxide anions or polyoxometalates (POMs) are reminiscent of the cooperative linear ABL distortions in perovskite d; metal oxides. We show herein that these distortions have a common origin:...
| Publicado en: | Journal of the American Chemical Society Vol. 130; no. 26; pp. 8223 - 8234 |
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| Autores principales: | , , , , , |
| Formato: | Artículo |
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American Chemical Society
7/2/2008
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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=33113240&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 33113240 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: 7/2/2008 vid: 130 iid: 26 pid: 997 pub: American Chemical Society artinfo: ui: 33113240 10.1021/ja711008n ppf: 8223 ppct: 11 formats: tig: atl: On the Origin of Alternating Bond Distortions and the Emergence of Chirality in Polyoxometalate Anions. aug: au: Likai Yan Lopez, Xavier Carbó, Jorge J. Sniatynsky, Richard Duncan, Dean C. Poblet, Josep M. affil: Institute of Functional Material Chemistry, Department of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel-Il Domingo s/n, 43007 Tarragona, Spain Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 532 11-3029 su: Metallic oxides Chirality Perovskite Density functionals Quantum chemistry sug: subj: Metallic oxides Chirality Perovskite Density functionals Quantum chemistry ab: Alternating short and long bond length (ABL) distortions observed within the ring structures of molecular metal oxide anions or polyoxometalates (POMs) are reminiscent of the cooperative linear ABL distortions in perovskite d; metal oxides. We show herein that these distortions have a common origin: a pseudo Jahn-Teller (PJT) vibronic instability. Four POM structural types with different MO ring sizes are investigated herein using density functional theoretical methods: Lindqvist [MO] (n = 4), Keggin α-[XMO] (n = 6), WelIs-Dawson α-[XMO] (n = 8), and Preyssler [(Na)PWO] (n = 10), where M = Mo and W and X = Si, Ge, P, As, S, and Se. Chirality is induced within the latter three structural types by the ABL ring distortions. The calculations confirm the PJT vibronic origin of the ABL distortions with good agreement between calculated geometries and published single-crystal X-ray diffraction data. Both theory and experiment show that the vibronic interaction and distortion magnitude increase for (1) molybdates relative to that of tungstates, (2) larger MO ring sizes, (3) increases in negative charge of the internalized fragments (O or XO), and (4) d versus d metal oxidation states. The PJT vibronic coupling model explains these observations in terms of the energy gap between Kohn-Sham frontier molecular orbitals (MOs) concomitant with the propensity for metal-oxygen π-bonding within the MO rings. The frontier MOs for the undistorted nuclear configurations are largely nonbonding π-O (occupied) and π-M (unoccupied) in character, where smaller HOMO-LUMO (H-L) gap energies lead to greater metal-oxygen π-orbital mixing under the influence of the nuclear distortion. A reduction in π-bond order decreases the distortion in mixed-valence POMs. Of the tungstates examined, only the Preyssler anion shows pronounced ABL ring distortions, which derive from its large ring size and concomitant small H-L gap. 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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