A Dichalcogenide-Protected Pt@Au12@Ag8 Nanocluster

Abstract Precise control over the location of heterometal atoms in alloy nanoclusters is essential for understanding how metal distribution governs superatomic structure and properties. Herein we show that PtAg20[S2P(OPr)2]12 (PtAg20) can serve as a structurally defined precursor for constructing a PtAu12 superatom copassivated by ligands and Ag atoms through redox-mediated Au-for-Ag exchange. Treatment of PtAg20 with an excess of Au(I) affords PtAu12Ag8[S2P(OPr)2]12 (PtAu12Ag8), in which substitution of Ag by Au occurs exclusively on the PtAg20 icosahedral core. Single-crystal X-ray diffraction reveals a compact PtAu12 core encapsulated by two Ag4(dtp)6 (dtp = dithiophosphate) units. Unlike all the known silver-rich isoelectronic nanoclusters featuring a centered icosahedron protected by a Ag8(dtp)12 outer shell that adopt C3-type or C3-derived shell arrangements, PtAu12Ag8 displays a C2 geometry. Spectroscopic and mass-spectrometric measurements support the formation of the Au-rich cluster, while DFT calculations identify the [PtAu12]4+ core as an eight-electron superatom with a closed-shell 1S21P61D0 electronic configuration. This work demonstrates that selective replacement of the icosahedral cage can generate not only a new trimetallic superatomic core but also an unusual reconstruction of the surrounding Ag–ligand passivating layer.