Structural and Electronic Origins of Dopant Site Selectivity in Atomically Precise Gold Nanoclusters

Heteroatom doping is an effective strategy for tuning the stability and electronic properties of atomically precise metal nanoclusters; however, the physical origins of dopant site selectivity remain incompletely understood, particularly beyond the superatomic regime. In this work, we present a systematic theoretical investigation of monodoped gold nanoclusters, M@Aux (M = Ag, Pd, Pt, Ir), including clusters within and beyond the superatomic framework. By comparing the relative energetics of central- and edge-substituted isomers across a series of clusters, we reveal the general trends in dopant site preference. Our results show that transition-metal dopants such as Pt, Pd, and Ir consistently favor highly coordinated central positions, whereas Ag doping shows a weaker and less systematic site selectivity. Furthermore, we show that the dopant site selectivity for transition metals arises from a dual origin: a structure-driven contribution associated with the local coordination and bonding environment that operates across all investigated systems, and an electronic contribution that becomes more pronounced for superatomic systems as a result of the symmetry-dictated interaction involving dopant d states and superatomic orbitals. Electronic structure analysis of Pt-doped clusters shows that central substitution promotes stronger mixing between Pt d orbitals and cluster-derived electronic states, whereas edge substitution results in more localized Pt-derived frontier states and higher relative energies. Extension of the analysis to Pd-, Pt-, and Ir-doped clusters reveals a systematic increase in the magnitude of dopant site selectivity following the trend Pd < Pt < Ir. Our findings provide general insights into the factors governing dopant stability in metal nanoclusters and offer guidance for the rational design of heteroatom-doped nanomaterials.