A Reliable Quantum-Chemical Protocol for the Characterization of Organic Mixed-Valence Compounds.
Structures, dipole moments, electron-transfer barriers, and spin density distributions of a series of mixed-valent bistriarylamin radical cations have been studied systematically by hybrid density functional methods with variable exact-exchange admixture combined with a continuum solvent model. The...
| Published in: | Journal of the American Chemical Society Vol. 131; no. 44; pp. 16292 - 16303 |
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| Main Authors: | , , , |
| Format: | Article |
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American Chemical Society
11/11/2009
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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=45585817&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 45585817 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: 11/11/2009 vid: 131 iid: 44 pid: 997 pub: American Chemical Society artinfo: ui: 45585817 10.1021/ja9070859 ppf: 16292 ppct: 11 formats: tig: atl: A Reliable Quantum-Chemical Protocol for the Characterization of Organic Mixed-Valence Compounds. aug: au: Renz, Manuel Theilacker, Koija Lambert, Christoph Kaupp, Martin affil: Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany su: Organic compounds Dipole moments Charge exchange Solvents Acetonitrile Cations Hartree-Fock approximation Density functionals sug: subj: Organic compounds Dipole moments Charge exchange Solvents Acetonitrile Cations Hartree-Fock approximation Density functionals ab: Structures, dipole moments, electron-transfer barriers, and spin density distributions of a series of mixed-valent bistriarylamin radical cations have been studied systematically by hybrid density functional methods with variable exact-exchange admixture combined with a continuum solvent model. The chosen systems differ in their bridging units and are all relatively close, from both sides, to the class II/III borderline of the Robin-Day classification of mixed-valence systems. Solvent effects are found to have a dramatic influence on the localized vs delocalized character of these cations. While gas-phase calculations or computations in a nonpolar solvent place all systems on the delocalized class Ill side, a more polar solvent like acetonitrile enables observation of symmetry breaking and charge localization with moderate exact- exchange admixtures in a hybrid functional for the systems on the class II side (with diphenylbutadiyne and diphenylethyne bridges). In contrast, the cations with the shortest bridges (phenylene, biphenylene) are characterized as class Ill. The comparison of computed intervalence charge-transfer excitation frequencies with experiment confirms the system with the diphenylbutadiyne bridge, and probably the system with the diphenylethyne bridge, to be class II, whereas in the dichloromethane solvent employed for spectroscopic measurements, the two other systems are on the class Ill side. Nonstandard hybrid density functional calculations with 35% Hartree-Fock-like exchange combined with continuum solvent models are suggested as a practical protocol for the quantum-chemical characterization of organic mixed-valence systems. This approach should allow closer examinations and provides a basis for the evaluation of other computational methods. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2009 holdings: @attributes: islocal: N |
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