Tin-Free Synthesis of 2,2′-Biphenyl Gold(III) Complexes Using Dibenzosilol

Abstract

Gold(III) complexes with dianionic 2,2′-biphenyl ligands stand out for their oxophilic Lewis acid character in combination with a stable and well-defined square planar geometry. They have been demonstrated to be unique and efficient chiral (pre)catalysts. Furthermore, their chemical and physical properties make them interesting for stoichiometric studies as well as organic electronics. These complexes are commonly prepared by transmetallating the bph ligand from undesirable and potentially toxic organotin compounds onto gold salts, making their synthesis problematic for health and the environment. Here, we present a tin-free synthesis using stable and nontoxic dibenzosilol as a transmetallating agent, accessing the same range of gold complexes as the dibenzostannanol-based synthesis. Furthermore, we confirm that corresponding isonitrile gold(III) complexes can be transformed into carbene gold(III) complexes by the nucleophilic attack of amines, opening up the route to new gold(III) catalyst design strategies.