Gold-2-Go

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The preparation of isolable mononuclear gold(II) complexes is apart from very few examples poorly developed. Spectroscopic and chemical properties of mononuclear gold(II) complexes are essentially unknown. Consequently, this project targets true mononuclear gold(II) complexes. Gold(II) complexes with idealized square-planar and T-shaped coordination geometry will be kinetically stabilized by using tetradentate macrocyclic ligands or tridentate sterically demanding chelate ligands which shall enable spectroscopic, magnetic and structural characterization. The “true” electronic nature (metal vs. ligand centered radical) will be elucidated. Spectroscopically confirmed gold(II) complexes will be studied by structural analyses with respect to expected first and second order Jahn-Teller distortions. The reactivity (dimerization, disproportionation, redox reactions, radical reactions with substrates) of this underdeveloped complex class will be systematically probed for the first time. Specifically, gold(II) complexes with coordination numbers three and four are targeted. Dimerization via Au-Au sigma bonds will be blocked by four ligand donor atoms in the xy plane in the former case and by steric protection of the free coordination site in the second case. Computer-aided screening of macrocylic and tridentate ligands will be performed using quantum chemical methods. The electronic structure of experimentally accessible gold(II) complexes will be verified employing advanced quantum chemical techniques using large basis sets. The project will lay the foundation to exploit the potential of gold(II) complexes in catalysis, redox catalysis and possibly photoredox catalysis.