We next examine the binding strength of ligands to Fe as quantified through the Mayer bond order to understand how the differences in binding of monodentate and bidentate succinate to Fe relate to their energetic stabilities in oxo and hydroxo intermediates. Consistent with prior work on intermediates with chloride, bidentate succinate binds more strongly to Fe than monodentate succinate but not as strongly as the bidentate aKG for intermediates with fluoride and bromide (Figure ). In general, binding strengths of succinate and aKG to Fe are slightly weaker in intermediates with fluoride compared to the larger chloride and bromide halides, both of which exhibit similar bond orders (Figure ). However, for Fe(III)-O2 intermediates, aKG binds more strongly to Fe when bromide/fluoride is in the active site compared to chloride, i.e., bond order of 1.40 vs 1.23 (Figure ). For Fe(II)-H2O intermediates with fluoride in the active site, the water molecule in the axial position can form a hydrogen bond (HB) with fluoride (Supporting Information Figure ). We find that aKG binds more strongly to Fe in the isomer with a HB between water and fluoride than it does in the isomer without the HB, i.e., bond order of 0.57 vs 0.47 (Figure ). Overall, binding strengths of ligands to Fe demonstrate limited dependence on the active site halide, with succinate and bidentate aKG displaying slightly stronger binding strengths for increasingly heavy halides (Figure ). Thus, the overall reactivity and bonding should be qualitatively similar regardless of halide. The stronger binding of aKG to Fe in Fe(III)-O2