A series of well‐defined copper(I) complexes bearing ring‐expanded N‐heterocyclic carbene (NHC) ligands has been applied to the azide–alkyne cycloaddition reaction. The obtained results notably showed that the six‐membered NHC ligands outperform well‐established five‐membered ones. [CuI(Mes‐6)] displayed a remarkable catalytic activity while respecting the strict criteria for click reactions.
