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Engineering the surface ligands of metal nanoparticles is critical in designing unique arrangements of metal atoms. Here, we report the synthesis and total structure determination of a large box-shaped Ag 67 nanocluster (NC) protected by a mixed shell of thiolate (2,4-dimethylbenzenethiolate, SPhMe 2 ) and phosphine (triphenylphosphine, PPh 3 ) ligands. Single crystal X-ray diffraction (SCXRD) and electrospray ionization mass spectrometry (ESI-MS) revealed the cluster formula to be [Ag 67 (SPhMe 2 ) 32 (PPh 3 ) 8 ] 3+ . The crystal structure shows an Ag 23 metal core covered by a layer of Ag 44 S 32 P 8 arranged in the shape of a box. The Ag 23 core was formed through an unprecedented centered cuboctahedron, i.e., Ag 13 , unlike the common centered Ag 13 icosahedron geometry. Two types of ligand motifs, eight AgS 3 P and eight bridging thiols, were found to stabilize the whole cluster. The optical spectrum of this NC displayed highly structured multiple absorption peaks. The electronic structure and optical spectrum of Ag 67 were computed using time-dependent density functional theory (TDDFT) for both the full cluster [Ag 67 (SPhMe 2 ) 32 (PPh 3 ) 8 ] 3+ and a reduced model [Ag 67 (SH) 32 (PH 3 ) 8 ] 3+ . The lowest metal-to-metal transitions in the range 500-800 nm could be explained by considering the reduced model that shows almost identical electronic states to 32 free electrons in a jellium box. The successful synthesis of the large box-shaped Ag 67 NC facilitated by the combined use of phosphine and thiol paves the way for synthesizing other metal clusters with unprecedented shapes by judicious choice of thiols and phosphines.

Molecular dynamics simulations using quantum mechanics for the electronic system, i.e., within the Born-Oppenheimer or related Car-Parrinello approximation, became feasible and popular in recent years for very large systems. The most common setup for these simulations is the supercell method in conjunction with the Γ-point approximation. Here we provide a tool which is useful to choose the supercell of the considered system such that it makes it appear to have either an as large as possible band gap (optimized for Car-Parrinello setup) or the metallic character reflected at the Γ point (e.g., fold the Dirac point to the Γ point for graphene and carbon nanotubes) in order to monitor the metallic character in a trajectory. We address carbon nanotubes, graphene, and inorganic TS2 analogues with T = Re, Nb. We further provide a simple Hückel code, which allows checking the electronic states close to the Fermi level within the Γ-point approximation, and we test its predictions against the density-functional-based tight-binding approach.