Low-nuclear Cu₄Cl₂ and Cu₂Cl₄ nanocluster specifically designed for A³ coupling reaction and mechanism insight

A³ coupling reaction is a three-component reaction widely used in pharmaceutical and is an important and practical method for constructing new C–N and C–C bonds. Here, two low-nuclear Cu₄Cl₂/C₃N₄ and Cu₂Cl₄/C₃N₄ catalysts were specifically designed for A³ coupling under mild conditions, with TON up to 8702.3 and 3461.8, respectively, much higher than reported catalysts. Additionally, we captured the key intermediate and confirmed its structures by electrospray ionization mass spectrometry (ESI-MS), revealing the halogen exchange process at the atomic level by experiments and density function theory (DFT) studies. These results increase our understanding of low-nuclear catalysts and provide guidance for the design and preparation of more efficient and targeted catalytic materials.