Executive Summary : | Transition metals in enzymes have led to the development of transition metal compounds for activating prototype bonds in small molecules. However, the near-degeneracy of valence orbitals in transition metal ions results in multiple or at least two low-lying electronic states with differing spin and electronic distribution. Schröder, Shaik, and Scwarz proposed the two-state reactivity (TSR) as a congener of single-state reactivity (SSR) in organometallic chemistry. The connection between multi-state situation and chemical reactivity has been explored in gas-phase reactions involving transition metal ions, such as the C-H/C-C bond activation by high valent metal oxo compounds. The probability of spin inversion competes with the barrier height in individual spin surfaces in dictating the reaction rate and product distribution. Electronic structure analyses can provide valuable information for understanding the reaction mechanism and proposing new experiments. Information such as optimized ground state geometry, physical oxidation state of metal cations, local spin states, composition of frontier molecular orbitals, and electronic distribution can help understand the reactivity of molecules involved. This project aims to explore and standardize theoretical methods to detect multi-/two-state reactivities of transition metal ions, which will be used to design and synthesize transition metal catalysts capable of activating small molecules, focusing on C-H/C-C bond activation. |