Metal–Metal Bonds in Catalysis

Transition metals can assemble to form multinuclear complexes by engaging in direct metal-to-metal interactions. Metal–metal covalent bonds provide a large perturbation in electronic structure, relative to mononuclear metal ions, and the unique properties of these dinuclear fragments can be harnessed in a broad range of applications—for example, as chromophores in photochemical processes, redox centers in molecular electronics, or structural elements in metal–organic materials. There is a growing body of evidence that metal–metal bonds may also be formed under conditions relevant to catalysis and play a key role in transformations that were previously assumed to only involve mononuclear species. These findings have stimulated interest in characterizing multinuclear reaction pathways and developing well-defined multinuclear platforms as catalytic active sites. In this Perspective, we present case studies in this emerging area of catalysis research, emphasizing the impact of metal–metal bonding in either en...