The Single-Centre Ambiphile ligand Concept: Cooperative Systems for Waste-free Catalysis

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The addition of ammonia to alkenes, which could produce amines in a 100% atom efficient process, has never been achieved by a molecular catalytic system and stands as a modern Holy Grail for the synthetic chemist. Alkyl amines, a major chemical commodity, are typically accessed through stoichiometric methods, even employing toxic N1 feedstocks such as hydrogen cyanide. The fundamental barrier to utilizing ammonia as an N1 feedstock lies in its activation, with a high N-H bond energy and a preference for acting as a neutral donor ligand in organometallic systems. In order to employ ammonia in catalytic transformations, new bond-activation concepts which address these fundamental pitfalls are essential. The SINGAMBI project overcomes these challenges through the Single-Centre Ambiphile (SCA) ligand concept. Drawing inspiration from cooperative activation protocols at play in enzymes and bimetallic complexes, this concept defines non-innocent ligand systems which utilise highly reactive ambiphilic species from the forefront of low-valent main group chemistry. In combination with reactive transition metal (TM) centres, SCA ligands provide a platform for cooperative bond scission via yet unexplored mechanistic pathways. This can drive facile ammonia activation, directing N-H bond cleavage towards the formation of TM hydride complexes, key in overcoming previous shortfalls in the hydroamination of alkenes with this abundant small molecule. Ultimately, we will expand this concept towards universal systems for waste-free alkene functionalisation catalysis, through forming a deep understanding of the unique mechanistic pathways accessible through the SCA ligand concept. In designing, developing and understanding numerous SCA-TM systems, the SINGAMBI project will develop a breadth of unique chemical tools for the promotion of cooperative bond activation and sustainable catalysis, framed by the activation and utilisation of ammonia for waste-free access to commodity amines.