Perspective: Exchange reactions in thiolate-protected metal clusters

Thiolate-protected metal clusters can exchange ligands or metal atoms with other substances such as coexisting ligands, complexes, and metal clusters in solution. Using these reactions, it is possible to synthesize metal clusters with new physical and chemical properties. Although the occurrence of such reactions was recognized nearly 20 years ago, their details were not well understood. In recent years, techniques for the precise synthesis of metal clusters and their characterization have progressed considerably and, as a result, details of these reactions have been clarified. In this perspective, we focus on the most-studied thiolate-protected gold clusters and provide a summary of recent findings as well as future expectations concerning the exchange reactions of these clusters.