The development of multi-metallic low oxidation state main-group compounds

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Catalytic chemical processes are the cornerstone of modern synthetic chemistry, with application in, for example, the large scale production of commodity chemicals, drug development and materials manufacturing. Many homogeneous catalytic processes are mediated by expensive precious metals which are often in limited supply, with perhaps the most famous examples based on the group 10 transition metals platinum and palladium. Attention in recent years has turned to finding Earth abundant and more cost effective alternatives to transition metals, with most early main-group elements fitting this profile. However, translation of chemical reactivity from transition metal complexes to main-group elements is far from trivial due to significant differences in the electronic configuration that ultimately controls their reactivity. Transition metals readily exist in multiple oxidation states, with interconversion between oxidation states driving redox (reductive elimination, oxidative addition) catalysis - one of the primary means of making and breaking chemical bonds. Main-group elements typically have one thermodynamically favoured oxidation state, which precludes facile redox chemistry. Recent years have seen advances in the isolation of main-group elements in thermodynamically unfavoured 'low oxidation states', with oxidative reactivity relatively well established. However, examples of reversible reactions (i.e. oxidative addition AND reductive elimination) are few and far between, with redox catalysis in the early main-group only inferred in a single case. The development of redox active main-group systems is therefore a major target in synthetic inorganic chemistry, which will ultimately lay the foundation for more sustainable and cost-effective chemical processes. This project will develop the redox chemistry of early main-group elements, creating unprecedented new low oxidation state metal complexes capable of oxidatively activating and reductively eliminating small, industrially relevant molecular fragments. The proposed research focuses on the development of multi-metallic low oxidation state complexes - compounds that contain two or more metals rich in electrons. These multi-metallic systems will have synergistic and cooperative effects, with metals in close proximity to one another benefiting from enhanced reactivity through metal orbital interactions and the complementary activity of metal sites. Understanding the underlying bonding structure and fundamental reactivity of these compounds is crucial for the continued development of redox chemistry in main-group compounds. The ultimate goal is to create a range of multi-metallic complexes from which stoichiometric reactivity can be translated to catalysis.