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 Au2 Ag42 (SAdm)27 (BPh4 ) and [Au2 Ag48 (S-t Bu)20 (Dppm)6 Br11 ]Br(BPh4 )2 nanoclusters. The crystallographic analysis reveals that both nanoclusters have a Au2 Ag24 core made of two separated icosahedral without sharing metal atoms, and each icosahedron has an eight-electron (8e) closed shell (1S2 1P6 ). The valence electronic structures of these two nanoclusters are analogous to that of a Ne atom dimer (Ne2 ) 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.