Alkyne–azide cycloaddition catalyzed by a dinuclear copper(I) complex

A novel dinuclear copper complex CuI2(pip)2 was used as a catalyst for alkyne–azide cycloaddition (CuAAC) reaction. High yields (95–99%) were obtained for various substrates at a low loading of 0.2 mol %. The unique structure, high stability of the dinuclear structure in solution, and easy preparation make this complex not only a high-efficiency catalyst but also a model for understanding the mechanism of the CuAAC reaction.