Ligand-Dependent Multi-State Reactivity in Cobalt(III)-Catalyzed C–H Activations

Cobalt­(III)-promoted C–H activation reactions have witnessed explosive progress in recent few years. However, the roles played by the various spin states of Co­(III) center in C–H activation reactivity remain elusive. To resolve this conundrum, herein we go beyond the commonly used DFT methods to explore three typical Co­(III)-promoted C–H activation systems. Our high-level coupled cluster modelings demonstrate that multistate reactivity (MSR) involving three spin states operates for C­(sp2)–H and C­(sp3)–H activations with non-Cp-Co­(III) type catalyst, while single-state reactivity (SSR) involving only one singlet spin state operates for C­(sp2)–H activation with Cp-Co­(III) type catalyst. This ligand-dependent reaction scenario of MSR/SSR reveals the high complexity in mechanisms of Co­(III)-promoted C–H activations.