(iii) The activation barrier for the ligand exchange via TS30-31_X is mainly reliant on the nature of the X-ligand and increases along with the coordinating ability of the X-ligand. This is because it involves a late transition structure, evident from the notable elongation of the I-X bond from 29_X to TS30-31_X (Figure ). The stronger the I-X bond, the more destabilized the transition structure TS30-31_X, and the higher the activation barrier to ligand exchange.