From Superatomic Au25(SR)18- to Superatomic M@Au24(SR)18q Core-Shell Clusters

Au-25(SR)(18)(-) belongs to a new type of superatom that features an icosahedral Au-13 core-shell structure and a protective layer of six RS(Au-SR)(2) motifs. This superatom has a magic number of 8 free electrons that fully fill the 1s and 1p levels of the electron-shell model. By applying this superatom concept to the core-substitution chemistry of Au-25(SR)(18)(-), we first scanned the periodic table for the potential core atom M by applying a simple rule derived from the 8-electron count and then optimized the selected candidates by density functional theory calculations to create many series of M@Au-24(SR)(18)(q) core-shell nanoclusters. We found that 16 elements from groups 1, 2, and 10-14 of the periodic table can maintain both electronic and geometric structures of the original Au-25(SR)(18)(-) magic cluster, indicating that the electron-counting rule based on the superatom concept is powerful in predicting viable M@Au-24(SR)(18)(q) clusters. Our work opens up a promising area for experimental exploration.