Next considering the metal-hydroxo intermediate, we find that the Ru-hydroxo species exclusively have positive DEI-L(hydroxo) values, most of which have large magnitudes (ca. 36 kcal/mol on average, Figure and Supporting Information Figure ). While we observe a positive relationship between ligand field strength and Ru DEI-L(hydroxo) values, the large positive values of DEI-L(hydroxo) nevertheless suggest that the Ru-hydroxo intermediates favor a LS state irrespective of the coordinating ligands (Supporting Information Figure ). Thus, the existence of an IS Ru-hydroxo species is highly unlikely, justifying our earlier choice to model HAT with Ru complexes via b-radical transfer. For the Fe-hydroxo species, omitting an outlier with a highly negative DEI-L(hydroxo) value, we find that the distribution of DEI-L(hydroxo) has an average of 0 kcal/mol (ranging from -25 kcal/mol to 21 kcal/mol, Figure and Supporting Information Figure ). Furthermore, we see that this distribution is similarly influenced by ligand field strength with both IS and LS states can be accessible (Figure and Supporting Information Figure ). These Fe catalysts with small magnitudes of DEI-L(isopropanol-bound) predominantly contain weak-field ligands while Fe catalysts with relatively larger DEI-L(isopropanol-bound) values comprise moderate-and strong-field ligands (Supporting Information Figure ). Thus, ligand field strength influences the ground state spin of the radical rebound intermediates in Fe catalysts. In specific outlier cases, some Fe catalysts comprising monodentate nitrogen-coordinating ligands have unexpectedly large, positive DEI-L(isopropanol-bound) values, suggesting a strong preference for the LS state, which leads to highly favorable isopropanol release in the unstable IS state, as discussed earlier.