A 34-Electron Superatom Ag78 Cluster with Regioselective Ternary Ligands Shells and Its 2D Rhombic Superlattice Assembly.

Herein, we report a 78-nuclei silver nanocluster (NC) [Ag78 (i PrPhS)30 (dppm)10 Cl10 ]4+ (SD/Ag78a; dppm=bis-(diphenylphosphino)methane) that was synthesized through a one-pot reaction using [Ag(pz)]n as precursor (Hpz=pyrazole) and further characterized by X-ray crystallography. SD/Ag78a shows a core-shell structure comprised of an all-metallic Ag53 kernel surrounded by an Ag25 discontinuous metal-organic shell. The Ag53 kernel is an Ag13 Ino decahedron encaged by an Ag40 drum-like shell, while the Ag25 shell consists of two Ag10 S10 P10 Cl5 rings and five S-Ag-S staples. Three types of ligands regioselectively cap on the surface of the Ag78 NC, forming diverse metal-ligand interfacial structures. The NC is a closed-shell 34-electron superatom with +4 charge state and shows highly featured molecule-like absorption spectra in the UV/Vis region with a maximum around 493 nm. The rhombic superlattice assembled from SD/Ag78a through intercluster C-H⋅⋅⋅π interactions can be formed by a simple drop-casting treatment.