[Ag20{S2P(OR)2}12]: A Superatom Complex with a Chiral Metallic Core and High Potential for Isomerism

The synthesis and structural determination of a silver nanocluster [Ag20{S2P(OiPr)2}12] (2), which contains an intrinsic chiral metallic core, is produced by reduction of one silver ion from the eight‐electron superatom complex [Ag21{S2P(OiPr)2}12](PF6) (1) by borohydrides. Single‐crystal X‐ray analysis displays an Ag20 core of pseudo C3 symmetry comprising a silver‐centered Ag13 icosahedron capped by seven silver atoms. Its n‐propyl derivative, [Ag20{S2P(OnPr)2}12] (3), can also be prepared by the treatment of silver(I) salts and dithiophosphates in a stoichiometric ratio in the presence of excess amount of [BH4]−. Crystal structure analyses reveal that the capping silver‐atom positions relative to their icosahedral core are distinctly different in 2 and 3 and generate isomeric, chiral Ag20 cores. Both Ag20 clusters display an emission maximum in the near IR region. DFT calculations are consistent with a description within the superatom model of an 8‐electron [Ag13]5+ core protected by a [Ag7{S2P(OR)2}12]5− external shell. Two additional structural variations are predicted by DFT, showing the potential for isomerism in such [Ag20{S2P(OR)2}12] species. Chiral silver nanocluster: The structure of an intrinsically chiral Ag20 nanocluster was determinded. Containing a silver‐centered icosahedron capped by seven silver atoms, it was rationalized to be an eight‐electron superatom complex. Isomeric Ag20 cores with distinct symmetry were characterized in two derivatives (nPr C1; iPr C3). DFT was used to predict the presence of additional structural variations to show rich isomerism in the Ag20 metallic core.