Synthesis of the First Gold(I) Carbene Complex with a Gold‐Oxygen Bond — First Catalytic Application of Gold(I) Complexes Bearing N‐Heterocyclic Carbenes

Abstract A series of silver(I) and gold(I) carbene complexes of the type [Ag(R2‐imy)2]+[AgBr2]— and [Au(R2‐imy)X] (R2‐imy = 1‐diphenylmethyl‐3‐methyl‐imidazol‐2‐ylidene; X = Cl, OC(O)CH3) have been prepared and structurally characterized. The complex [Au(R2‐imy) OC(O)CH3] is the first gold(I) carbene complex with a gold‐oxygen bond. The results of a single crystal structure determination of this gold(I) carbene acetate are similar to those of the analogous (triphenylphosphane)gold(I) acetate. The gold oxygen distance Au‐O1 with 2.040(4)Å parallels the majority of (phosphane)gold(I) carboxylates. Furthermore we successfully employed the Au(I) carbene acetate as a catalyst for the addition of water to 3‐hexyne in the presence of a Lewis acid as co‐catalyst. This is the first example for the use of a gold(I) carbene complex in homogeneous catalysis.