Electrochemical C–H bond activation via cationic iridium hydride pincer complexes† †Electronic supplementary information (ESI) available. CCDC 1935784, 1935785 and 1935786. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c9sc03076j

• Published in: Chemical science (Cambridge) 2019-08, Vol.10 (40), p.9326-9330
• Main Authors: Lindley, Brian M., Walden, Andrew G., Brasacchio, Ann Marie, Casuras, Andrea, Lease, Nicholas, Chen, Chun-Hsing, Goldman, Alan S., Miller, Alexander J. M.
• Format: Article
• Language: English
• Subjects: Chemistry
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c9sc03076j

Electrochemical C–H activation proceeds at room temperature upon oxidation of a pincer-ligated iridium complex in the presence of base. A C–H bond activation strategy based on electrochemical activation of a metal hydride is introduced. Electrochemical oxidation of ( t Bu 4 PCP)IrH 4 ( t Bu 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 [( t Bu 4 PCP)IrH(L)] + (where L = pyridine, 2,6-lutidine, or 2-phenylpyridine). Facile deprotonation of [( t Bu 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 ( t Bu 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.