Spectroscopic Manifestations and Implications for Catalysis of Quasi‐d10 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 CuIII complex [Cu(CF3)4]1−, in which the metal center tries to populate its formally unoccupied 3dx2‐y2 orbital via σ‐bonding, leading to a reduced d10 CuI description. However, Au L3‐edge X‐ray absorption spectroscopy reveals excitation into the d‐orbital of the AuIII species is still possible, showing that a genuine d10 configuration is not achieved. We also find an increased electron‐sharing nature of the σ‐bonds in the AuI species, relative to their AgI and CuI 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 5dx2‐y2 or 6s orbital, respectively, in bonding, indicating why AuI and AuIII complexes often have similar reactivity. Through the interplay of X‐ray spectroscopy and computational analysis, we show that gold +I and +III complexes, despite their physically distinct electronic structures, tend to activate substrates to similar extents. We focus in particular on the role of electron‐sharing covalency of the metal‐ligand bonds and provide an explanation for the often‐similar reactivities observed for gold complexes in these physical oxidation states.