Bonding of Two 8-Electron Superatom Clusters

We report the observation of dimerization of two 8-electron superatom cluster units in the crystallographic structures of Au2Ag42(SAdm)(27)(BPh4) and [Au2Ag48(S-Bu-t)(20)(Dppm)(6)Br-11]Br(BPh4)(2) nanoclusters. The crystallographic analysis reveals that both nanoclusters have a Au2Ag24 core made of two separated icosahedral without sharing metal atoms, and each icosahedron has an eight-electron (8e) closed shell (1S(2)1P(6)). The valence electronic structures of these two nanoclusters are analogous to that of a Ne atom dimer (Ne-2) according to the density functional theory (DFT) analysis. This is the first crystallographic observation of the dimerization of 8-electron superatom units. This study enriches the fundamental knowledge on metal superatom clusters and implies the possibility for further assembling metal superatom building blocks into higher order superatom molecules.