Base-Triggered Oxidative Addition to Gold.

Area of Science:

• Organometallic Chemistry
• Catalysis
• Gold Chemistry

Background:

• Gold complexes are increasingly utilized in catalysis.
• Activation of aryl-iodide bonds is crucial for cross-coupling reactions.
• Secondary phosphine oxides (SPO) are versatile ligands in coordination chemistry.

Purpose of the Study:

• To investigate the promotion of C(sp2)-I bond activation by gold complexes coordinated with SPO.
• To elucidate the mechanism of this novel transformation.
• To explore the electronic factors influencing the reaction and derivatization of resulting complexes.

Main Methods:

• Gold-catalyzed cross-coupling reactions.
• Use of secondary phosphine oxides (SPO) as ligands.
• Addition of a base (e.g., NEt3, K2CO3).
• Computational analysis (Density Functional Theory).

Main Results:

• SPO ligands efficiently promote gold-catalyzed C(sp2)-I bond activation in the presence of a base.
• The reaction proceeds via a new type of chelation-assisted oxidative addition.
• Computational studies indicate the oxidative addition is dominated by Au→(Ar-I) backdonation.
• This mechanism differs from previously reported electron-deficient cationic gold(I) complexes.
• Access to (P=O,C)-cyclometallated Au(III) complexes is achieved.
• The SPO moiety on Au(III) can be chemically derivatized (protonation, silylation).

Conclusions:

• Secondary phosphine oxides are effective ligands for gold-catalyzed C(sp2)-I bond activation.
• The mechanism involves chelation assistance and significant Au→(Ar-I) backdonation.
• This work expands the scope of gold catalysis and provides access to functionalized Au(III) complexes.