Encapsulating Hydrides and Main-Group Anions in d10-Metal Clusters Stabilized by 1,1-Dichalcogeno Ligands

Cu(I) and Ag(I) can form with 1,1-dithio(seleno) ligands various types of clusters, the framework of which being maintained by the metal-chalcogen bonds provided by the bridging ligands. The metal centers are generally tricoordinated and consequently possess an accepting orbital of valence s and/or p character. There is no formal metal-metal bonding, but only weak d(10)-d(10) interactions which favor the overlap between the metal accepting orbitals. Their bonding combinations are generally suited for interacting with the occupied valence orbitals of an encapsulated anion. Thus, many of these clusters are able to encapsulate anions, a situation which tends to stabilize the whole structure through building of significant host-guest bonding. Not only is the anion encapsulation effect to stabilize the cluster cage, but it can also significantly modify its structure, or act as a template in the stabilization of species which would not exist as empty clusters. This paper reviews the synthesis, structure and bonding of all the known clusters of d(10) metals decorated with 1,1-dichalchogeno ligands and containing entrapped atomic anions. Their structures are analyzed with respect to size and shape. The photoluminescence properties of some of them are discussed.