(vi) The energy barrier of the redox step (transformation 22_X  TS22-23_X) is particularly sensitive to the nature of the X-ligand. As the coordinating ability of the X-ligand increases, the activation barrier to this step increases (see the ΔG ‡ 1 values in Table ). Consequently, a strong coordinating X-ligand alleviates the electron deficiency of the iodine(V) center in 22_X, making it less susceptible to be involved in the redox step. This hypothesis finds support from the inspection of the NPA charge on the iodine atom in 22_X, which increases along the series from +2.544 in 22_OAc to +2.568 in 22_OTf (Figure ). Also, this feature causes the redox step for a relatively strong coordinating X-ligand to take place via a later transition structure (TS22-23_X), consistent with the shortest C … O distance in TS22-23_OAc (2.125 Å) and the longest one in TS22-23_OTf (2.164 Å, Figure ).