MeMe-BONDS · Group 1 and Group 2 Metal-Metal Bonds. Tailored Reduction Reagents in Synthesis and Catalysis.

The increasing demand for environmentally friendly reagents to perform sustainable processes has become of paramount relevance for modern academia and industry. Transition metal-based catalysts are long-established players in many important chemical transformations, given their ability to cleave and form chemical bonds with facile oxidation state changes. Their high cost and/or toxicity, however, have prompted the search for potential replacements. The past decades brought fascinating discoveries of main-group-based species exhibiting low-oxidation states and/or metal–metal bonds with excellent and tunable reducing properties. Nonetheless, despite formidable efforts invested in broadening the scope, existing examples are restricted to Mg-containing molecules, while other s-block metal-metal bonds remain unaccomplished. MeMe-BONDS will address this challenge by engineering novel sustainable reductants based on hitherto unknown s-block bonds stabilized by tunable electronic interactions. This breakthrough will be possible by combining the steric shielding provided by commonly used ligands with the introduction of a σ-acceptor functionality to tame the inherent reactivity of formed radical intermediates. This innovative metal-ligand interaction will allow for the precise incorporation of one or two extra electrons, resulting in a unique electronic structure, which - under suitable conditions - will afford the new s-block metal–metal bonds. Tandem experimental and computational methods will enable a fundamental understanding of the electronic structures and their interplay with the nature of the substituents. The properties and reactivity of these novel bonds will be thereby tuned, opening the door for application in small molecules’ activation and as electronically versatile catalysts. The output of this project will enrich the synthetic chemistry toolbox and pave the way for more environmentally friendly chemical processes.