Insights into the Mechanism of Low-Valent Cobalt-Catalyzed C–H Activation
João C. A. Oliveira, Uttam Dhawa, Lutz Ackermann
Abstract
The use of cobalt complexes of N-heterocycle carbene (NHC) ligands as catalysts for C–H activation is extremely advantageous due to their low costs and high efficiencies at room temperature. These catalysts have been proposed to operate in low oxidation states and have successfully been applied in C–H alkylations as well as C–H arylations, among others. Despite these indisputable advances, detailed mechanistic insights into their exact working mode continue to be scarce. Herein, we present extensive DFT and DLPNO-CCSD(T) computational studies, which provide strong support for a mechanism via low-valent cobalt-catalyzed C–H activations. Our findings indicate the key C–H metalation to proceed through a ligand-to-ligand hydrogen transfer (LLHT) pathway rather than a classical oxidative addition mechanism.