Trinuclear Gold Clusters Supported by Cyclic (alkyl)(amino)carbene Ligands: Mimics for Gold Heterogeneous Catalysts

The synthesis of air‐ and moisture‐stable trinuclear mixed‐valence gold(I)/gold(0) clusters is described. They promote the catalytic carbonylation of amines under relatively mild conditions. The synthetic route leading to the trinuclear clusters involves a simple ligand exchange from the readily available μ3‐oxo‐[(Ph3PAu)3O]+ complex. This synthetic method paves the way for the preparation of a variety of mixed‐valence gold(I)/gold(0) polynuclear clusters. Moreover, the well‐defined nature of the complexes demonstrates that the catalytic process involves a rare example of a definite change of oxidation state of gold from Au02AuI to AuI3. Well‐defined clusters supported by three cyclic (alkyl)(amino)carbenes (CAACs), or two CAACs and a phosphine, can be prepared by ligand exchange. These mixed‐valence gold(I)/gold(0) clusters promote the catalytic carbonylation of amines by the formation of di‐ or trinuclear gold(I) complexes, which can be isolated.