Copper(I) Complexes Bearing Carbenes Beyond Classical N-Heterocyclic Carbenes: Synthesis and Catalytic Activity in "Click Chemistry"

The synthesis and characterization of abnormal N‐heterocyclic carbene, cyclic (alkyl)(amino)carbene, and mesoionic carbene copper(I) complexes are reported. These organometallic species are obtained via a versatile and inexpensive synthetic pathway using readily available reactants, namely copper oxide and iminium salts. The catalytic activity of this series of complexes was evaluated in the [3+2] cycloaddition of alkynes with azides (CuAAC). Outstanding catalytic properties were observed for the abnormal NHC‐ and triazolylidene‐based copper(I) complexes.