For the (2, 2, 1) cluster, we find both a halogen bond (bond 20 in Figure ) and an apparent I 3 O - 8 . The halogen bond, at about 2.53 Å, is significantly longer than the newly formed, presumable covalent bond (17, highlighted in green in Figure ), which is approximately 2.18 Å. The I ). However, these interatomic distances are still consistent enough that the assignment of an intra-cluster covalently bound I 3 O - 8 complex is highly probable. At the very least a covalent-like interaction is taking place at bond 17. In order to determine with more confidence whether this interaction is halogen bonding at play between an iodine pentoxide molecule and iodate molecule or if in fact an I 3 O - 8 covalent complex is forming, more sophisticated theoretical analysis will be required.