Single-Step Synthesis of Dinuclear Neutral Gold(I) Complexes with Bridging Di(N-heterocyclic carbene) Ligands and Their Catalytic Performance in Cross Coupling Reactions and Alkyne Hydroamination

We report on a single-step procedure for the synthesis of dinuclear gold(I) complexes with bridging di(N-heterocyclic carbene) (diNHC) ligands of general formula Au2Br2L1-9 (L = diNHC). The obtained complexes differ in the bridging group between the carbene donors and in the terminal wingtip substituents at the imidazol-2-ylidene rings. The complexes have been characterized by means of elemental analysis, NMR spectroscopy, ESI-MS spectrometry, and single-crystal X-ray structure analysis. The dinuclear gold(I) complexes have been tested as homogeneous catalysts in technologically relevant reactions such as the cross coupling between phenylboronic acid and aryl bromides and the intermolecular hydroamination of alkynes. The catalytic performance has been compared for complexes Au2Br2L1-9 and the benchmark mononuclear complex IPrAuCl.