This barrier height is in the middle range of those reported in prior work. Specifically, it is slightly lower than the HAT reaction barriers of ca. 30 kcal/mol observed for BesD in prior work owing to additional constraints used in that study. In comparison to another study, we find that the HAT barriers we observe are higher by ca. 5 kcal/mol, likely because we evaluate HAT reaction using first coordination sphere residues and a model substrate whereas first and second coordination sphere residues along with the complete substrate are used to compute HAT barrier in this other work. We also find that the hydroxo intermediate along with the substrate radical formed after HAT are higher in energy by ca. 10-13 kcal/mol relative to the reactants, i.e., the oxo intermediate and substrate, across all three halides (Figure ). The high-energy structures along the RCs observed at an O•••H distance of 1.18 Å are confirmed to be transition states through Hessian calculations and the presence of a single imaginary frequency along the HAT RC (Figure and Supporting Information Table ). Furthermore, we obtained optimized geometries of these transition states along with the corresponding Hessian calculations with a single imaginary frequency along the HAT RC (Supporting Information Table and Figure ). Next, we study rebound RCs in which the substrate radical reacts with hydroxo or halide ligands (Figure ). Rebound reactions with hydroxo/halide are carried out using the most stable bidentate succinate isomers with axial hydroxo/halide, which are comparable in energy (Figure ).