Electrochemical C–H bond activation via cationic iridium hydride pincer complexes

A C–H bond activation strategy based on electrochemical activation of a metal hydride is introduced. Electrochemical oxidation of ((tBu(4))PCP)IrH(4) ((tBu(4))PCP is [1,3-((t)Bu(2)PCH(2))-C(6)H(3)](–)) in the presence of pyridine derivatives generates cationic Ir hydride complexes of the type [((tBu(4))PCP)IrH(L)](+) (where L = pyridine, 2,6-lutidine, or 2-phenylpyridine). Facile deprotonation of [((tBu(4))PCP)IrH(2,6-lutidine)](+) with the phosphazene base tert-butylimino-tris(pyrrolidino)phosphorane, (t)BuP(1)(pyrr), results in selective C–H activation of 1,2-difluorobenzene (1,2-DFB) solvent to generate ((tBu(4))PCP)Ir(H)(2,3-C(6)F(2)H(3)). The overall electrochemical C–H activation reaction proceeds at room temperature without need for chemical activation by a sacrificial alkene hydrogen acceptor. This rare example of undirected electrochemical C–H activation holds promise for the development of future catalytic processes.