Investigation of the changes in hydrogen bonding accompanying the structural reorganization at 103 K in ammonium iodate

Abstract

Neutron powder diffraction has been used to observe the changes in hydrogen bonding that occur as a function of temperature in ND 4 IO 3 and, thus, determine the structural features that occur during the low-temperature (103 K) phase transition. It is shown that in the deuterated material the change is not a phase change per se but rather a structural reorganization in which the hydrogen bonding becomes firmly locked in at the phase transition temperature, and stays in this configuration upon further cooling to 4.2 K. In addition, both the differences and changes in the axial thermal expansion coefficients in the region 100-290 K can be explained by the changes involving both the hydrogen bonding and the secondary IÁ Á ÁO halogen bonds.

High-pressure induced switching between halogen and hydrogen bonding regimes in 1,4-dioxane iodine monochloride

“…31 Many such interactions were noted encompassing both inorganic, e.g. in ferroelectric ammonium iodate 32,33 and organic examples, including the thyroxine molecule (T3), which is used in the treatment of hypothyroidism, where an extremely close I⋯O contact was observed. 34 These interactions were generally subsumed under the title of secondary interactions and have been extensively reviewed by Alcock.…”