Facile Formation of Homoleptic Au(III) Trications via Simultaneous Oxidation and Ligand Delivery from [PhI(pyridine)2]2+

We report the first examples of Au­(III) tricationic complexes bound only by neutral monodentate ligands, which are a new class of gold reagents. Oxidative addition to the bis-pyridine Au­(I) cation, [Au­(4-DMAP)2]+, using a series of dicationic I­(III) oxidants of the general form [PhI­(L)2]2+ (L = pyridine, 4-DMAP, 4-cyanopyridine) allows ready access to homoleptic and pseudo-homoleptic Au­(III) complexes [Au­(4-DMAP)2(L)2]3+. The facile oxidative addition of Au­(I) species additionally demonstrates the efficacy of PhI­(L)2]2+ reagents as halide-free oxidants for Au­(I). Comparisons are made via attempts to oxidize NHC-Au­(I)­Cl, where introduction of the chloride anion results in complex mixtures via ligand and chloride exchange, demonstrating the advantage of using the pyridine-based homoleptic compounds. The new Au­(III) trications show intriguing reactivity with water, yielding dinuclear oxo-bridged and rare terminal Au­(III)−OH complexes.