As seen in Figure , both iodic and iodous acid bonds through hydrogen-bonding, however, it can be seen that iodic acid also shows a propensity towards halogen bonds in the form of I-O coordination, as seen for (IA) 1 (MSA) 1 , (IA) 2 . (IA) 2 structurally resembles the iodine pentoxide structure, which can be seen in Figure in Section S1 of the SI. This tendency is likely due to the extra oxygen allowing for this interaction to occur side-by-side with the acid-base reaction. presents the lowest free energy clusters containing iodine tetroxide (IT) and pentoxide (IP). A pattern equivalent to the one seen for iodic acid is found, where we primarily observe I-N and I-O coordination, as seen for the (IP) 1 (TMA) 1 and (IT) 2 clusters. However we also observed hydrogen-bonding behavior in combination with I-N coordination, see (IT) 1 (NA) 1 and (IT) 1 (SA) 1 . For (IT) 1 (NA) 1 , we see that iodine tetroxide is able to act as a base in the presence of nitric acid, this is also seen for (IT) 1 (FA) 1 but not for any of the other acids. It is not observed for any of the IP clusters.