Superatomic or Not? A Case Study on Isostructural Au3Ag2 and Au3Cu2 Nanoclusters.

Abstract

Two bimetal nanoclusters, [Au3Ag2(Ppy3)6](NO3)3 (Au3Ag2) and [Au3Cu2(Ppy3)6](BF4)3 (Au3Cu2) have been synthesized with tri(2-pyridyl)phosphine (Ppy3). 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. Au3Ag2 demonstrates much better stability than Au3Cu2 in solution. Theoretical calculations indicate that Au3Ag2 is the smallest well-defined superatom while Au3Cu2 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.