Macrocyclic tetranuclear copper (I) complex bearing a N-heterocyclic carbene ligand: Synthesis, structure, and catalytic properties

A rare macrocyclic tetranuclear copper (I) complex ([Cu4(2)2](PF6)4) of phenanthroline-based NHC ligand has been prepared and characterized by NMR, ESI-MS spectroscopy, and X-ray diffraction analysis. The complex displays a novel twisted macrocyclic conformation and weak intramolecular Cu–Cu interactions. The complex is found to exhibit high catalytic activity in the Cu-catalyzed azide–alkyne cycloaddition (CuAAC) reaction in an air atmosphere at room temperature in a MeCN/H2O mixture solution.