Iodine in clathrate hydrate cages

CHED 998

Reid K. Smith, and Lisa B. Lewis, Department of Chemistry, Albion College, Albion, MI 49224
At low temperatures or high pressures, water can form polyhedral cages around guest molecules. These hydrogen-bonded structures are referred to as clathrate hydrates. The empty lattice is not thermodynamically stable and the van der Waals interactions between the guest molecules and the water molecules stabilize the structure. The guest size defines the morphology of the clathrate hydrate and iodine is expected to form the sII clathrate hydrate (512 and 51264 cages in a 2:1 ratio). Chlorine and bromine form stable structures; however, clathrates containing iodine have only been stabilized in the presence of a second guest molecule. We present our work that shows that iodine alone can form a stable ice structure that melts above 0 oC.