Interconversion between Superatomic 6-Electron and 8-Electron Configurations of M@Au24(SR)18 Clusters (M = Pd, Pt)

Kyuju Kwak, Qing Tang, Minseok Kim, De En Jiang, Dongil Lee

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Abstract

The exceptional stability of thiolate-protected Au25 clusters, [Au25(SR)18]-, arises from the closure of superatomic electron shells, leading to a noble-gas-like 8-electron configuration (1S21P6). Here we present that replacing the core Au atom with Pd or Pt results in stable [MAu24(SR)18]0 clusters (M = Pd, Pt) having a superatomic 6-electron configuration (1S21P4). Voltammetric studies of [PdAu24(SR)18]0 and [PtAu24(SR)18]0 reveal that the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps of these clusters are 0.32 and 0.29 eV, respectively, indicating their electronic structures are drastically altered upon doping of the foreign metal. Density functional investigations confirm that the HOMO-LUMO gaps of these clusters are indeed smaller, respectively 0.33 and 0.32 eV, than that of [Au25(SR)18]- (1.35 eV). Analysis of the optimized geometries for the 6-electron [MAu24(SR)18]0 clusters shows that the MAu12 core is slightly flattened to yield an oblate ellipsoid. The drastically decreased HOMO-LUMO gaps observed are therefore the result of Jahn-Teller-like distortion of the 6-electron [MAu24(SR)18]0 clusters, accompanying splitting of the 1P orbitals. These clusters become 8-electron [MAu24(SR)18]2- clusters upon electronic charging, demonstrating reversible interconversion between the 6-electron and 8-electron configurations of MAu24(SR)18.

Original languageEnglish
Pages (from-to)10833-10840
Number of pages8
JournalJournal of the American Chemical Society
Volume137
Issue number33
DOIs
Publication statusPublished - 2015 Jul 29

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All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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