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(sp(2))-H and C(sp(3))-H activations with non-Cp-Co(III) type catalyst, while single-state reactivity (SSR) involving only one singlet spin state operates for C(sp(2))-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.