On Heteronuclear Isoelectronic Alternatives to [Au(dppe)Cl]: Electronic and Optical Properties of the 18-Electron Os@[Au(dppe)Cl] Cluster from Relativistic Density Functional Theory Computations.

The development of well-defined atomically precise heteronuclear nanoclusters passivated by protecting ligands is presently a booming area, owing to the fact that doping well-known homonuclear nanostructures allows fine-tuning of their properties. Here, we explore by means of density functional theory calculations the possibility of doping the central gold atom in the classical [Au(dppe)Cl]cluster () by Os. Although both [Au(dppe)Cl] and [Os@Au(dppe)Cl] have the same total number of electrons, we show that they are not isoelectronic within the formalism of the superatom model, being respectively an 8- and an 18-electron species. It results that they exhibit similar structures but present significantly different optical behaviors (ultraviolet/visible and circular dichroism). Similar results are obtained for the Ru and Fe relatives. Emission properties indicate some redshift of the T→S decay with respect to [Au(dppe)Cl], involving an equatorial distortion of the AuCl core in the T state, rather than the axial distortion afforded by . The sizable highest occupied molecular orbital-lowest unoccupied molecular orbital gaps found for the three doped species suggest that further experimental exploration of different stable doped species derived from the ligand-protected AuCl core should be encouraged.