Gold peroxide complexes and the conversion of hydroperoxides into gold hydrides by successive oxygen-transfer reactions

Abstract

Gold catalysts are widely studied in chemical and electrochemical oxidation processes. Computational modelling has suggested the participation of Au-OO-Au, Au-OOH or Au-OH surface species, attached to gold in various oxidation states. However, no structural information was available as isolable gold peroxo and hydroperoxo compounds were unknown. Here we report the syntheses, structures and reactions of a series of gold(III) peroxides, hydroperoxides and alkylperoxides. The Au-O bond energy in peroxides is weaker than in oxides and hydroxides; however, the Au-OH bond is also weaker than Au-H. Consequently Au-OH compounds are capable of oxygen-transfer generating gold hydrides, a key reaction in a water splitting cycle and an example that gold can react in a way that other metals cannot. For the first time it has become possible to establish a direct connection from peroxides to hydrides: Au-OO-Au-Au-OOH-Au-OH-Au-H, via successive oxygen-transfer events.

Stereo‐ and Regioselective Alkyne Hydrometallation with Gold(III) Hydrides

“…Given that square‐planar gold(III) compounds of type 1 stabilized by rigid pincer ligands have no coordination sites available for substrate binding, the mechanism of this alkyne hydroauration was not obvious. Earlier computational attempts to search for the coordination of a phosphine to the metal perpendicular to the molecular plane had failed to find any evidence for an energy minimum . Computations with an alkyne as a possible ligand gave analogous results: there was no evidence for a coordinative alkyne–gold interaction.…”

Cyclometalated Gold(III) Complexes: Synthesis, Reactivity, and Physicochemical Properties

“…[49] First, (15) with tert-butyl hydroperoxide in toluene at room temperature.S imilarly,t he reaction of 15 with 30 % aqueous hydrogen peroxide produced the Au III -hydroperoxide complex [(C^N^C)AuOOH] (28). Taking advantage of the stable Au III -hydroxo complex [(C^N^C)AuOH] (15)a nd the [(C^N^C)AuH] complex 24, Bochmann and co-workers set out to intensively study the intrinsic reactivity of Au III À Ob onds in this context (Scheme 7).…”

Formation of Gold(III) Alkyls from Gold Alkoxide Complexes

“…7 The existence of competing alternative reaction channels in the transformation of 1 to 2 was also indicated by the appearance of signals due to the known 11 Au(II) complex (C ∧ N ∧ C)Au–Au(C ∧ N ∧ C) ( 3 ). The final 2 : 3 molar ratio was 3:1.…”

“…7 Following the same bond strength trend, gold hydrides can even be formed from suitable reactive gold–carbon compounds, such as Au–COOH species, where facile transformation to the hydride by CO 2 elimination was observed. 8 Calculations also show that the O abstraction from the gold methoxide 1 to give the gold methyl complex 2 is energetically favorable (Scheme 1).…”