Free energy landscapes of select Fe and Ru complexes were obtained using ORCA v5.0.1 113 with the B3LYP functional with D3 dispersion correction using Becke-Johnson damping. The def2-TZVP basis set 114 was employed for Fe and Ru atoms while the def2-SVP basis set 114 was used for all other atoms. Starting from TeraChem-optimized structures, we completed additional DFT geometry optimizations to obtain thermochemical corrections on the intermediates. We used ORCA for the free energy landscape calculations because TeraChem does not support analytical Hessians. Transition states were optimized on ORCA by first computing potential energy surface (PES) scans where the presumed transition state mode, such as a bond length, was incrementally changed and fixed while geometry optimizing all other degrees of freedom. The maxima from these PES scans were used as initial guesses for a partitioned rationalfunction optimization (P-RFO) 115 to locate the transition state structures. Transition state structures were verified by performing frequency calculations to ensure than an imaginary frequency corresponding to the expected transition state mode was observed and intrinsic reaction coordinate (IRC) 116 calculations to confirm the equilibrium points connecting a transition state structure.