The free energy landscapes further substantiate the spin-reactivity trends we proposed from the spin splitting energy analyses. In our full catalytic cycle analysis, Fe catalysts predominantly undergo a spin-allowed C-H hydroxylation pathway on the IS state surface while Ru catalysts undergo a spin-forbidden pathway, transitioning between the LS and IS states (Figure and Supporting Information Figures ). For a subset of complexes, D and F, selected for the ease of convergence of those specific intermediates, we performed minimum energy crossing point (MECP) calculations on their Ru analogues (see Sec. 3). The MECP characterization confirms that the first spin crossover from the LS to the IS state during metal-oxo formation step occurs after the metal-oxo formation transition state (TS1) while the second spin crossover back to the LS state occurs during the radical rebound step (Supporting Information Table ). We also find that the barriers for metal-oxo formation are lower in this subset of Ru catalysts (ca. 24 kcal/mol for D and 15 kcal/mol for F in LS states and 14 kcal/mol for D and 4 kcal/mol for F in IS states) than their corresponding Fe catalysts (ca. 35 kcal/mol for D and 27 kcal/mol for F in LS states and 23 kcal/mol for D and 21 kcal/mol for F in IS states). For HAT, we observe the opposite trend where the Fe catalysts generally have lower barriers (ca. 9 kcal/mol for D and 13 kcal/mol for F in LS states and 12 kcal/mol for D and 6 kcal/mol for F in IS states) than their Ru counterparts (ca. 16 kcal/mol for D and 19 kcal/mol for F in LS states and 19 kcal/mol for D and 21 kcal/mol for F in IS states) (Figure ). This trend also holds more generally across all the six catalysts for which we computed reaction coordinates (Supporting Information Figures ). Furthermore, these kinetic trends align with the energetic trends for the metal-oxo formation and HAT steps, suggesting the existence of correlations between Fe and Ru C-H hydroxylation reaction energetics and kinetics, which we will return to in further detail.