Eight-Electron Silver and Mixed Gold/Silver Nanoclusters Stabilized by Selenium Donor Ligands.

The first atomically and structurally precise silver-nanoclusters stabilized by Se-donor ligands, [Ag {Se P(O Pr) } ] (3) and [Ag {Se P(OEt) } ] (4), were isolated by ligand replacement reaction of [Ag {S P(O Pr) } ] (1) and [Ag {S P(O Pr) } ] (2), respectively. Furthermore, doping reactions of 4 with Au(PPh )Cl resulted in the formation of [AuAg {Se P(OEt) } ] (5). Structures of 3, 4, and 5 were determined by single-crystal X-ray diffraction. The anatomy of cluster 3 with an Ag core having C symmetry is very similar to that of its dithiophosphate analogue 1. Clusters 4 and 5 exhibit an Ag and Au@Ag core of O symmetry composed of eight silver capping atoms in a cubic arrangement and encapsulating an Ag and Au@Ag centered icosahedron, respectively. Both ligand exchange and heteroatom doping result in significant changes in optical and emissive properties for chalcogen-passivated silver nanoparticles, which have been theoretically confirmed as 8-electron superatoms.