A high pressure study of hydrogen and halogen bonding in ND4ICl2

Hydrogen and halogen bonding are two of the most important intermolecular forces in chemistry and biology. NH4ICl2 consists of NH4+ and ICl2− ions, the latter of which deviates considerably from the symmetric geometry most often encountered. One of the I-Cl distances is at the upper end of those previously reported for this ion; and is intermediate in length between an I-Cl bond and an I---Cl halogen bond, with the chlorine atoms involved in several hydrogen bonds of varying strength. The other I-Cl bond is closer to that seen in ICl. NQR studies suggest that electronic structure of the ICl2− ion alters upon cooling to liquid nitrogen temperature because of changes in the reorientational motion of the ammonium ion. We will carry out a variable pressure experiment to investigate how hydrogen and halogen bonding respond to pressure and how change in one force will affect the other.