An Atomically Precise Alkynyl‐Protected PtAg₄₂ Superatom Nanocluster and Its Structural Implications

The synthesis and structure determination of an alkynyl‐protected Pt‐doped Ag superatom nanocluster, [PtAg 42 (C≡CC 6 H 4 CH 3 ) 28 ](SbF 6 ) 6 (1) , are reported. The metallic core of this cluster can be viewed as a concentric three‐shell Russian doll comprising Pt@Ag 12 @Ag 30 , in which the missing icosidodecahedral Ag 30 shell and a new structural unit, M 43 , have been observed. On the surface of 1 , 28 alkynyl groups and 4 SbF 6 − anions were found co‐protecting it. The protective role of SbF 6 − in nanoclusters is unprecedented. Moreover, of the 28 alkynyl ligands, 12 are connected not only with the outermost Ag 30 shell, but also the inner Ag 12 shell through the twelve pentagonal faces of the outermost icosidodecahedral Ag 30 shell. Overall, by determining the crystal structure of 1 , we discovered the missing icosidodecahedral Ag 30 shell and the protective effect of SbF 6 − anions and demonstrated a novel M 43 structural unit and the unique penetrability of pentagonal faces.