[Au (SR) ] , As Smaller 8-Electron Gold Nanocluster Retaining an SP -Core. Evaluation of Bonding and Optical Properties from Relativistic DFT Calculations.

Exploring the versatility of atomically precise clusters is a relevant issue in the design of functional nanostructures. Superatomic clusters offer an ideal framework to gain further understanding of the different distinctive size-dependent physical and chemical properties. Here, we propose [Au (SR) ] as a minimal 8-electron superatom related to the prototypical [Au (SR) ] cluster, depicting half of its core-mass (2.3 kDa vs 5.0 kDa). The [Au (SMe) ] cluster fulfills a 1S 1P electronic configuration, with a distorted tetrahedral Au core further viewed as an SP -hybridized superatom. The distinctive optical properties show a blue-shift for the first relevant 1P→1D transition, in comparison to [Au (SR) ] . In addition, chiroptical activity is observed, denoting intrinsic core chirality. We expect that our results can shed light into the variation of the molecular properties according to the size-dependent properties, and serve as guidelines for further experimental exploration of minimal or ultrasmall nanoclusters.