Direct Evidence for Intermolecular Oxidative Addition of σ(SiSi) Bonds to Gold

Abstract

Oxidative addition plays a major role in transition-metal catalysis, but this elementary step remains very elusive in gold chemistry. It is now revealed that in the presence of GaCl3, phosphine gold chlorides promote the oxidative addition of disilanes at low temperature. The ensuing bis(silyl) gold(III) complexes were characterized by quantitative (31)P and (29)Si NMR spectroscopy. Their structures (distorted Y shape) and the reaction profile of σ(Si-Si) bond activation were analyzed by DFT calculations. These results provide evidence for the intermolecular oxidative addition of σ(Si-Si) bonds to gold and open promising perspectives for the development of new gold-catalyzed redox transformations.

Gold‐Catalyzed Cross‐Coupling Reactions: An Overview of Design Strategies, Mechanistic Studies, and Applications

“…[243][244][245] They used the design principle of starting with the disilane reactants containing one or two phosphine ligandsi ns uitable positions, which can cushion or act as buttresses with Au in the transition state and later form bonds with the metal in thep roduct (Scheme 46 a). [243,244] (b) Oxidation of disilane-Au III forming the disiloxane-Au III complex. Experimental NMR kinetic studies and DFT calculations showed that the presence of two phosphine ligands led to larger chelating effects and decreased the energy barrier for the oxidative addition.…”

Controlling the oxidative addition of aryl halides to Au(I)

“…Although gold is able to undergo transmetallation, insertion, and reductive elimination reactions, the Au(I)→Au(III) oxidative addition remains comparatively highly elusive . In this regard, no direct evidence for oxidative addition of C sp2 X bonds at a single gold center has been obtained so far, (For a computational study of C sp2 −F bond activation at gold, see Ref.…”

Oxidative Addition of Carbon–Carbon Bonds to Gold

“…Similar results were obtained, indicating that the kinetic preference for C(aryl)ÀC(O) bond activation and thermodynamic preference for C(alkyl)ÀC(O) bond activation are intrinsic of the [(DPCb)Au] + complex. In addition, analysis of the transition states TS 5 and TS 6 by the activation strain model [18] indicates minimal contribution of the DE°d ist-[(DCPb)Au+] distortion term to the activation barrier DE° (Table S3), as in the case of Ph À I activation.…”

“…However, the ability of gold(I) complexes to an undergo oxidative addition of s-bonds, such as S À S, Si À Si, Sn À Sn, and C(aryl) À X bonds, has been recently demonstrated in intramolecular [5] as well as intermolecular versions. [6] In particular, we recently reported that rationally designed twocoordinate cationic gold(I) complexes [(DPCb)Au] + (DPCb = diphosphino-carborane) with a bent PAuP angle (ca. 1008) readily achieve the oxidative addition of aryl iodides, a transformation that was so far considered highly disfavored, if not impossible, with gold.…”