Substituent Effects and the Mechanism of Gold to Alkene Benzylidene Transfer Employing a Gold Sulfonium Benzylide Complex

Combining ligand-enhanced backdonation and steric shielding to stabilize a mono-substituted Au(I) carbene

A mono-substituted Au(I) carbene was prepared by reacting HC(N₂)(Dmp) (Dmp = 2,6-dimesitylphenyl) with an (o-carboranyl)-diphosphine AuNTf₂ complex. It is stable up to -10 °C and was characterized by NMR spectrocopy. According to DFT calculations, the chelating P^P ligand enhances Au → C_carb backdonation, while the Dmp substituent provides kinetic stabilization but does not bias the electronic structure of the carbene complex.