This review describes the chemistry of anionic mixed 1516 clusters and their coordination chemistry with transition metals. The focus is on the heavier elements such as sulfides and selenides of phosphorus, arsenic and antimony. A brief introduction with a historical perspective is followed by the chemistry of soluble anionic clusters, including preparative methods and structural characteristics. Solids containing recognizable anionic fragments (Zintl phases) are also described. Bonding is mentioned briefly. Transition metal complexes of these clusters are discussed in some detail and structures and bonding are highlighted. Neglected areas and future prospects are mentioned.