title: Computational and spectroscopic studies of organic mixed-valence compounds: where is the charge?
abstract: This article discusses recent progress by a combination of spectroscopy and quantum-chemical calculations in classifying and characterizing organic mixed-valence systems in terms of their localized vs. delocalized character. A recently developed quantum-chemical protocol based on non-standard hybrid functionals and continuum solvent models is evaluated for an extended set of mixed-valence bis-triarylamine radical cations, augmented by unsymmetrical neutral triarylamine-perchlorotriphenylmethyl radicals. It turns out that the protocol is able to provide a successful assignment to class II or class III Robin-Day behavior and gives quite accurate ground- and excited-state properties for the radical cations. The limits of the protocol are probed by the anthracene-bridged system 8, where it is suspected that specific solute-solvent interactions are important and not covered by the continuum solvent model. Intervalence charge-transfer excitation energies for the neutral unsymmetrical radicals are systematically overestimated, but dipole moments and a number of other properties are obtained accurately by the protocol.
authors: Technische Universität Berlin, Institut für Chemie, Theoretische Chemie, Sekr, C7, Straße des 17, Juni 135, 10623 Berlin, Germany. martin.kaupp@tu-berlin.de
authors: Martin
authors: M
authors: Kaupp
authors: Manuel
authors: M
authors: Renz
authors: Matthias
authors: M
authors: Parthey
authors: Matthias
authors: M
authors: Stolte
authors: Frank
authors: F
authors: Würthner
authors: Christoph
authors: C
authors: Lambert