Arylgold(I) Complexes from Base-Assisted Transmetalation: Structures, NMR Properties, and Density-Functional Theory Calculations

The synthesis of gold(I) complexes of the type LAuR (L = PCy(3), IPr; R = aryl; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) starting from LAuX (X = Br, OAc) and boronic acids in the presence of Cs(2)CO(3) has been investigated. The reactions proceed smoothly in good to excellent yields over the course of 24-48 h in isopropyl alcohol at 50-55 °C. The aryl groups include a variety of functionalities and steric bulk, and in two cases, are heterocyclic. All of the products have been characterized by multinuclear NMR spectroscopy and elemental analysis and most by X-ray crystallography. This work affirms that, almost without exception, base-assisted auration is a useful and reliable way to form gold-carbon bonds.