Emergence of Nido-Icosahedral Superatomic Units in Iridium-Doped Silver Cluster Assemblies.

The concept of superatomic building blocks provides a powerful framework for understanding the stability of nonspherical metal nanoclusters; however, assemblies derived from unconventional motifs remain largely underexplored. Herein, we report a series of iridium-doped, silver-rich 16-electron superclusters (nanoclusters constructed from the assembly of individual superatomic building units), (IrH2)2Ag31[S2P(OPr)2]17 (1), (IrH)(IrH2)Ag32[S2P(OPr)2]17 (2), and (IrH)2Ag33[S2P(OPr)2]17 (3), whose cores can be described as assemblies of two 8-electron superatomic units. Single-crystal X-ray diffraction, complemented by density functional theory (DFT) calculations, reveals that clusters 1 and 2 feature an unprecedented eight-electron nido-icosahedral core, IrH2Ag11, which arises as a defective motif induced by multiple hydrides. The three isolated clusters establish a formal structural relationship in which each successive composition differs by one Ag atom and one hydride, highlighting the relationship among hydride incorporation, electron count, and structural topology in superclusters. Furthermore, these clusters exhibit systematic variations in their spectroscopic properties, including a progressive red shift of their lowest-energy absorption bands, consistent with their tunable electronic structures. This work not only identifies a new type of superatomic building unit but also demonstrates that hydrides can act as key regulators of both electronic configuration and structural topology, providing important insights into how hydride-induced defects can be harnessed to expand the structural diversity and electronic modularity of noble metal nanoclusters.