title: [Cu6(NGuaS)6]2+and its oxidized and reduced derivatives: Confining electrons on a torus.
abstract: The hexanuclear thioguanidine mixed-valent copper complex cation [Cu6(NGuaS)6]+2(NGuaS = o-SC6H4NC(NMe2)2) and its oxidized/reduced states are theoretically analyzed by means of density functional theory (DFT) (TPSSh + D3BJ/def2-TZV (p)). A detailed bonding analysis using overlap populations is performed. We find that a delocalized Cu-based ring orbital serves as an acceptor for donated S p electrons. The formed fully delocalized orbitals give rise to a confined electron cloud within the Cu6S6cage which becomes larger on reduction. The resulting strong electrostatic repulsion might prevent the fully reduced state. Experimental UV/Vis spectra are explained using time-dependent density functional theory (TD-DFT) and analyzed with a natural transition orbital analysis. The spectra are dominated by MLCTs within the Cu6S6core over a wide range but LMCTs are also found. The experimental redshift of the reduced low energy absorption band can be explained by the clustering of the frontier orbitals. © 2017 Wiley Periodicals, Inc.
authors.affiliation: Lehrstuhl für Bioanorganische Chemie, Fachgruppe Chemie, RWTH Aachen University, Landoltweg 1, Aachen, 52074, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Witte
authors.affiliation: Lehrstuhl für Theoretische Physik, Universität Paderborn, Warburger Str. 100, Paderborn, 33098, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Rohrmüller
authors.affiliation: Lehrstuhl für Theoretische Physik, Universität Paderborn, Warburger Str. 100, Paderborn, 33098, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Gerstmann
authors.affiliation: Lehrstuhl für Anorganische Chemie, Universität Paderborn, Warburger Str.100, Paderborn, 33098, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Henkel
authors.affiliation: Lehrstuhl für Theoretische Physik, Universität Paderborn, Warburger Str. 100, Paderborn, 33098, Germany.
authors.forename: Wolf Gero
authors.initials: WG
authors.lastname: Schmidt
authors.affiliation: Lehrstuhl für Bioanorganische Chemie, Fachgruppe Chemie, RWTH Aachen University, Landoltweg 1, Aachen, 52074, Germany.
authors.forename: Sonja
authors.identifier: 0000-0002-4354-4353
authors.initials: S
authors.lastname: Herres-Pawlis
keywords: charge decomposition analysis; copper thiolate complexes; density functional theory; time-dependent-DFT