DFT calculations were performed to gain insight into the underlying causes of the variation in observed rate constants between complexes 2, 3 and corresponding ligands 6, 7. Table lists experimentally derived and calculated activation energies, ΔGact, and details of the calculated transition state geometries are given in the SI. Experimentally, both the directly bound triazine species, 2/6 and the phenathroline species, 3/7, show a lowering of the activation energy on complexation, which is also reflected in the calculations. Additionally, the experimental trend of the phenanthroline species having higher activation energies than the equivalent directly bound triazine species is echoed by the calculations, along with the larger drop in activation energy on complexation for the directly bound triazine than the phenanthroline.