Mechanisms in Heterobimetallic Reactivity

In this chapter, the authors discuss indiscriminately examples of heterobimetallic complexes which feature metal–metal bonds as well as complexes in which metal sites have been compartmentalized by tailored ligand architecture. The activation of small molecules such as hydrogen, nitrogen, or carbon dioxide is an attractive approach to synthetic chemistry. The authors describe how heterobimetallic catalysts have been developed for polymerization reactions, including for sustainable polymers such as the ring-opening of lactones and the ring-opening copolymerization of epoxides and carbon dioxide. One of the most efficient methods to synthesize polyolefins is via the coordination insertion polymerization using transition metal catalysts. Evidence that the desired heterobimetallic complexes retain their structure and composition under the conditions of catalysis is paramount to confirm any metal cooperativity and validate any mechanistic investigation that will feed into a subsequent catalyst design process. One challenge in heterobimetallic catalysis is confirming any metal cooperative effect and understanding its origin.