[Cu6(NGuaS)6]2+ and its oxidized and reduced derivatives: Confining electrons on a torus. Issue 20 (10th April 2017)

• Record Type: Journal Article
• Authors: Witte, Matthias; Rohrmüller, Martin; Gerstmann, Uwe; Henkel, Gerald; Schmidt, Wolf Gero; Herres‐Pawlis, Sonja
• Is Part Of: Journal of computational chemistry. Volume 38:Issue 20(2017)
• Page Start: 1752
• Page End: 1761
• Publication Date: 2017-04-10
• Subjects: density functional theory -- time‐dependent‐DFT -- copper thiolate complexes -- charge decomposition analysis; Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.24798
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract : The hexanuclear thioguanidine mixed‐valent copper complex cation [Cu6 (NGuaS)6 ] +2 (NGuaS = o‐SC6 H4 NC(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 Cu6 S6 cage 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 Cu6 S6 core 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. Abstract : The [Cu6 (NGuaS)6 ] 2+ and its oxidized and reduced derivatives are theoretically studied by means of density functional theory (DFT). The hexagonal shaped Cu6 S6 core forms a delocalized torus for electrons and becomes larger on reduction. A detailed population analysis shows donor and acceptor contributing MOs from the metal core and ligands. The experimental UV/Vis absorption response is analyzed with time‐dependent DFT and the absorption bands are assigned to explicit charge transfer transitions.