Understanding the Surprising Oxidation Chemistry of Au−OH Complexes

Au is known to be fairly redox inactive (in catalysis) and bind oxygen adducts only quite weakly. It is thus rather surprising that stable Au−OH complexes can be synthesized and used as oxidants for both one‐ and two‐electron oxidations. A charged Au(III)−OH complex has been shown to cleave C−H and O−H bonds homolytically, resulting in a one‐electron reduction of the metal center. Contrasting this, a neutral Au(III)−OH complex performs oxygen atom transfer to phosphines, resulting in a two‐electron reduction of the hydroxide proton to form a Au(III)−H rather than causing a change in oxidation state of the metal. We explore the details of these two examples and draw comparisons to the more conventional reactivity exhibited by Au(I)−OH. Although the current scope of known Au−OH oxidation chemistry is still in its infancy, the current literature exemplifies the unique properties of Au chemistry and shows promise for future findings in the field.