Neutral Five‐Coordinate Arylated Copper(III) Complex: Key Intermediate in Copper‐Mediated Arene Trifluoromethylation

Comprehensive Summary Five‐coordinate neutral Cu(III) complexes have long been considered as the key intermediates in copper‐mediated/catalyzed arene trifluoromethylative reactions, but the identity of these complexes remains elusive. Herein, we reported, for the first time, the preparation and characterization of these putative complexes [(bpy)Cu(CF3)2(C6F4R)] and investigation of their C(sp2)‐CF3 bond‐forming reductive elimination. Our mechanistic studies including kinetic studies, the effect of temperature and solvents, the effect of the para‐substitution of the ligand as well as DFT calculations suggest that C(sp2)‐CF3 reductive elimination process proceeds via synchronous bond‐breaking/bond‐forming process. Elusive key intermediates five‐coordinate neutral arylated Cu(III) complexes in copper‐mediated trifluoromethylation of arenes were characterized and Ar‐CF3 reductive elimination processes from these complexes were studied for the first time.