Enlightening open shell 3d metal complexes through compressed ligand fields

• Applicants: Giovanni Li Manni, Ph.D.; Professorin Dr. Birgit Weber
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation ; Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 509879467

There are very few examples of open-shell 3d metal complexes that show luminescence. The aim of this project is to find out which requirements must be met in the interaction of ligand and metal center in order to observe luminescence for complexes with a luminescent ligand backbone. The focus is set on diamagnetic nickel(II) complexes with a square planar ligand field and octahedral low-spin iron(II/III) and cobalt(III) complexes. A special focus will be given the concept of a compressed ligand field, realized through macrocyclic ligands of the Jäger-type, to tailor the ligand field splitting. In addition to the synthesis and comprehensive spectroscopic characterization of the new complexes, the understanding of the photophysical properties will be supported by extended theoretical considerations. Conventional TD-DFT calculations will be complemented by the application of state-of-the-art theoretical techniques based on the stochastic optimization of large active space wave functions (Stochastic-CASSCF) and on-top pair density functionals (via MC-PDFT), for the latter techniques accurately describe the strong correlation effects and long-range entanglements between metal center and ligand electrons. The unique experiment/theory cooperation represents an opportunity to understand, predict and set fundamental rules on the rare luminescent processes for open-shell 3d metal complexes.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Gerald Hörner