How CuCl and CuCl₂ Insert into C-N Bonds of Diazo Compounds: An Electronic Structure and Mechanistic Study

The transition-metal Cu catalysts CuCl and CuCl₂ have been widely employed to catalyze a series of chemical reactions with diazo compounds because of their high efficiency and selectivity. However, how to yield the active Cu carbene species from the Cu catalysts and diazo compounds still remains unclear. In this work, we performed a comprehensive theoretical investigation on the electronic structures of CuCl and CuCl₂ in solution. The results indicate that the most stable structures for CuCl and CuCl₂ are dimer and monomer, respectively. The C-N bond insertion of aryldiazoacetate by CuCl yields a stable bimetallic carbene species, which differs from the monometallic carbene generated from CuCl₂.