Diversifying Al(I) chemistry: from Al(I) starting materials to novel electronic structures of aluminium complexes in low redox states

• Applicant: Professor Dr. Philipp Dabringhaus
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 583382217

The research project aims to diversify Al(I) chemistry and establish a novel class of aluminium ambiphiles for the controlled activation of small molecules. The long-term goal is the development and detailed understanding of controllable redox-active aluminium complexes for the application in redox-catalysis. This project is expected to develop the foundation to achieve this ambitious goal. In the start of the project, the preparation of easily accessible starting materials for Al(I) complexes is investigated. In these compounds, simple Al(I) salts are stabilized with simple leaving groups and/or weakly-coordinating ligands, which can be easily replaced with stronger donor ligands to in situ generate highly reactive complexes. Promising ligands are crown ethers, anthracene, or small amines and phosphines. The successful preparation will enable access to a diverse follow-up chemistry. The novel starting materials will be used in the preparation of Al-pincer complexes with a novel electronic structure. In these complexes, the p-orbital at the Al is incorporated in the reducing -system of a redox non-innocent ligand. In addition, a free coordination site at Al allows for a metal-centred Lewis acidity, achieving an ambiphilic reactivity at the aluminium metal. This unique electronic structure is unprecedented in Al chemistry and can be regarded as an inverse carbene structure. DFT calculations reveal a unique coordination chemistry of these complexes, predicting stable CO, alkene, and alkyne complexes. The redox activity of the T-shaped Al complexes in one- and two-electron transfer reactions and small-molecule activation will be studied. Aiming to achieve reversible substrate activation at an Al complex, the influences of oxidation of the complex or post-functionalization of the ligand backbone by ligand coordination on the reactivity of the Al complexes will be investigated. Hence, the reactivity of the Al complexes for elementary steps in redox catalysis will be studied intensively. These detailed reactivity studies are essential puzzle steps to achieve the design of full redox-cycles with Al complexes.

• DFG Programme: Research Grants