Icosahedral noble-metal 13-atom nanoclusters (NCs) can form connected structures, which can be regarded as superatomic molecules, by vertex sharing. However, there have been very few reports on the superatomic molecules formed using silver (Ag) as the base element. In this study, we synthesized [Ag23Pd2(PPh3)10Cl7]0 (Pd = palladium, PPh3 = triphenylphosphine, Cl = chloride), in which two icosahedral 13-atom NCs are connected, and elucidated its geometric and electronic structures to clarify what type of superatomic molecules can be synthesized. The results revealed that [Ag23Pd2(PPh3)10Cl7]0 is a synthesizable superatomic molecule. Single crystal x-ray diffraction analysis showed that the metal–metal distances in and between the icosahedral structures of [Ag23Pd2(PPh3)10Cl7]0 are slightly shorter than those of previously reported [Ag23Pt2(PPh3)10Cl7]0, whereas the metal–PPh3 distances are slightly longer. On the basis of several experiments and density functional theory calculations, we concluded that [Ag23Pd2(PPh3)10Cl7]0 and previously reported [Ag23Pt2(PPh3)10Cl7]0 are more stable than [Ag25(PPh3)10Cl7]2+ because of their stronger superatomic frameworks (metal cores). These findings are expected to lead to clear design guidelines for creation of new superatomic molecules.

Alloying has been studied actively for thiolate (SR)protected metal nanoclusters (NCs) because heteroatom mixing enables the creation of novel electronic structures, physical/chemical properties, and functions. Among them, SR-protected gold (Au)-based 25-atom alloy NCs (Au 25−x M x (SR) 18 ; M = heteroatom) are the most studied NCs. However, a geometrical structure of copper (Cu)-substituted [Au 25−x Cu x (SR) 18 ] − has not been determined by single-crystal X-ray diffraction (SC-XRD) analysis to date. In this study, we discovered suitable crystallization conditions for [Au 25−x Cu x (PET) 18 ] − (PET = phenylethanethiolate) and revealed by SC-XRD that Cu substitutes Au preferentially in the staple regardless of synthesis methods. Cu substitution also occurred at the surface of metal core when the number of Cu substitutions increased. The main Cu-substitution site can be changed from the staple to the surface of metal core when the central Au atom of the NCs is substituted by platinum. Experimental and theoretical results on the electronic structure indicate that the effect of Cu substitution on the electronic structure of Au-based 25-atom alloy NCs is similar to that of silver substitution. These findings are expected to lead to clear design guidelines to create NCs with new physical/chemical properties and functions.

To use atomically precise metal nanoclusters (NCs) in various application fields, it is essential to establish size-selective synthesis methods for the metal NCs. Previous studies on thiolate (SR)-protected gold NCs...

We recently found that [Pt 17 (CO) 12 (PPh 3 ) 8 ] z (Pt = platinum; CO = carbon monoxide; PPh3 = triphenylphosphine; z = 1+ or 2+) is a Pt nanocluster (Pt NC) that can be synthesized...

Extremely small metal clusters composed of noble metal atoms (M) have orbitals similar to those of atoms and therefore can be thought of as artificial atoms or superatoms. If these superatoms can be assembled into molecular analogs, it might be possible to create materials with new characteristics and properties that are different from those of existing substances. Therefore, the concept of superatomic molecules has attracted significant attention. The present review focuses on vertex‐shared linear M12n+1 superatomic molecules formed via the sharing of a single metal atom between M13 superatoms having icosahedral cores and summarizes the knowledge obtained to date in this regard. This summary discusses the most suitable ligand combinations for the synthesis of M12n+1 superatomic molecules along with the valence electron numbers, stability, optical absorption characteristics, and luminescence properties of the M12n+1 superatomic molecules fabricated to date. This information is expected to assist in the production of many M12n+1 superatomic molecules with novel structures and physicochemical properties in the future.