Spectroscopic Manifestations and Implications for Catalysis of Quasi‐d(10) Configurations in Formal Gold(III) Complexes

Several gold +I and +III complexes are investigated computationally and spectroscopically, focusing on the d‐configuration and physical oxidation state of the metal center. Density functional theory calculations reveal the non‐negligible electron‐sharing covalent character of the metal‐to‐ligand σ‐bonding framework. The bonding of gold(III) is shown to be isoelectronic to the formal Cu(III) complex [Cu(CF(3))(4)](1−), in which the metal center tries to populate its formally unoccupied 3d(x2‐y2) orbital via σ‐bonding, leading to a reduced d(10) Cu(I) description. However, Au L(3)‐edge X‐ray absorption spectroscopy reveals excitation into the d‐orbital of the Au(III) species is still possible, showing that a genuine d(10) configuration is not achieved. We also find an increased electron‐sharing nature of the σ‐bonds in the Au(I) species, relative to their Ag(I) and Cu(I) analogues, due to the low‐lying 6s orbital. We propose that gold +I and +III complexes form similar bonds with substrates, owing primarily to participation of the 5d(x2‐y2) or 6s orbital, respectively, in bonding, indicating why Au(I) and Au(III) complexes often have similar reactivity.