Atomically precise ultrasmall copper cluster for room-temperature highly regioselective dehydrogenative coupling

Three-component dehydrogenative coupling reactions represent important and practical methodologies for forging new C-N bonds and C-C bonds. Achieving highly all-in-one dehydrogenative coupling functionalization by a single catalytic system remains a great challenge. Herein, we develop a rigid-flexible-coupled copper cluster [Cu3(NHC)3(PF6)3] (Cu3NC(NHC)) using a tridentate N-heterocyclic carbene ligand. The shell ligand endows Cu3NC(NHC) with dual attributes, including rigidity and flexibility, to improve activity and stability. The Cu3NC(NHC) is applied to catalyze both highly all-in-one dehydrogenative coupling transformations. Mechanistic studies and density functional theory illustrate that the improved regioselectivity is derived from the low energy of ion pair with copper acetylide and endo-iminium ions and the low transition state, which originates from the unique physicochemical properties of the Cu3NC(NHC) catalyst. This work highlights the importance of N-heterocyclic carbene in the modification of copper clusters, providing a new design rule to protect cluster catalytic centers and enhance catalysis. Three-component dehydrogenative coupling reactions represent important and practical methodologies for forging new C-N bonds and C-C bonds but achieving all-in-one dehydrogenative coupling functionalization by a single catalytic system remains a great challenge. Here, the authors develop a rigid flexible-coupled copper using a tridentate N-heterocyclic carbene ligand to achieve dehydrogenative coupling using a single catalyst system.

Automated summary

Three-component dehydrogenative coupling reactions are important and practical methods for creating new C-N and C-C bonds, but achieving all-in-one dehydrogenative coupling functionalization through a single catalytic system remains a major challenge. In this study, a rigid-flexible-coupled copper cluster with a tridentate N-heterocyclic carbene ligand is developed to achieve dehydrogenative coupling using a single catalyst system.