A Tetrahedral Silver-Rich Supercluster Composed of 8-Electron IrH₂Ag₁₂ Icosahedra

Although the prediction of constructing three-dimensional self-assembled superclusters using icosahedral superatoms as building blocks dates back to 1987, this task remains a significant challenge, due to the difficulty in synthesizing and characterizing such clusters. In this study, the 8-electron superatom IrH₂Ag₁₉[S₂P(OⁿPr)₂]₁₂ (1) was discovered for the first time, with IrH₂ as the dopant. Its distinctive superatomic core, IrH₂Ag₁₂, was utilized as a building block for the self-assembly of a tetrahedral supercluster. A new hydride-containing 32-electron Ir/Ag alloy nanocluster, (IrH₂)₄Ag₅₀[S₂P(OⁿPr)₂]₂₂ (2), was prepared using homoleptic ligand. Similar to the prediction by Teo et al., the four icosahedra are assembled in a tetrahedral manner, which is reminiscent of tetrahedrane, to form the [(IrH₂)₄Ag₄₂]¹⁴⁺ core passivated by [Ag₈{S₂P(OⁿPr)₂}₂₂]^14-. Unlike previous studies that used M₁₃ units, this study uniquely utilizes four (IrH₂)@Ag₁₂ units sharing six vertices to achieve the tetra-icosahedral kernel. The discovery of this 3D supercluster can more effectively help us understanding the growing process from nanoclusters to nanoparticles.