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.