Superatomic or Not? A Case Study on Isostructural Au ₃ Ag ₂ and Au ₃ Cu ₂ Nanoclusters

Abstract Two bimetal nanoclusters, [Au 3 Ag 2 (Ppy 3 ) 6 ](NO 3 ) 3 ( Au 3 Ag 2 ) and [Au 3 Cu 2 (Ppy 3 ) 6 ](BF 4 ) 3 ( Au 3 Cu 2 ) have been synthesized with tri(2‐pyridyl)phosphine ( Ppy 3 ). Single crystal X‐ray structural analysis reveals that both have trigonal bipyramidal structures with three Au atoms at the waist and Ag/Cu atoms at the top and bottom vertices. Au 3 Ag 2 demonstrates much better stability than Au 3 Cu 2 in solution. Theoretical calculations indicate that Au 3 Ag 2 is the smallest well‐defined superatom while Au 3 Cu 2 is nonsuperatomic, even though they are isostructural and have the same number of valence electrons. This work highlights the influence of atom doping on the electronic structures and superatomic properties of metal nanoclusters.