From molecular Sb units to infinite chains, layers, and networks: Sb-Sb interactions in metal-rich antimonides

A multitude of metal-rich pnictides and chalcogenides of the valence-electron-poor transition elements M have been uncovered in recent years. Common structural features of all these compounds are extended metal atom substructures (of different kinds) and the occurrence of metal-pnicogen and metal-chalcogen bonds, respectively. Bonding homonuclear interactions between the main-group elements E are found only in the structures of the antimonides and bismuthides. This bonding situation is associated with highly complex crystal structures in the latter cases, because of the presence of three different types of bonding, i.e. M-E, M-M and E-E bonds.