Theoretical Analysis of the M₁₂Ag₃₂(SR)₄₀^4– and X@M₁₂Ag₃₂(SR)₃₀^4– Nanoclusters (M = Au, Ag; X = H, Mn)

We analyze the electronic structure and optical properties of the recently reported, structurally known M₁₂Ag₃₂(SR)₃₀^4– clusters (M = Au, Ag) by using density functional theory and time-dependent density functional perturbation theory. Effects of the chemical changes in the metal core, charge of the cluster, and nature of the thiolate ligand on the electronic structure and optical absorption are reported. In addition, doping the metal core with a magnetic transition metal atom (Mn) or hydrogen (protons) is discussed. Although all these clusters can be considered as 18-electron superatoms with a shell configuration 1S² 1P⁶ 1D¹⁰, we find that the optical spectrum is sensitive to the charge state and chemical composition of the core and that all optical transitions in the visible range have important contributions from the electron-rich aromatic ligands. Added protons work as counter-cations reducing the overall charge but keeping the stable 18-electron configuration. Finally, our calculations predict that doping the center hole of the metal core by a manganese atom makes the cluster a 20-electron superatom with a configuration 1S² 1P⁶ 1D¹⁰ 2S² but keeps the maximal spin-moment localized at the dopant in a Mn­(3d⁵) configuration by the Hund rule