2008 Eighth Annual Beckman Scholars Symposium
Saturday Poster Session - July 29, 2006

Halogen bonding is an important supermolecular interaction that can be exploited in both crystal engineering and in solution host-guest chemistry. A considerable amount of effort has gone into identifying supramolecular synthons involving oxygen and, especially, nitrogen donor systems. Here, we focus on the lesser-investigated interaction between sulfur compounds, particularly thioamides, with molecular iodine and various organoiodines. Single crystal X-ray diffraction of a series of halogen-bonded systems reveals reoccurring structural motifs, as well as instances where identifiable, competing interactions can break those motifs. Quantum mechanical methods were employed to better understand these observations. Using density functional theory, the energetics of the halogen bonds are calculated and an MO description of the systems is produced. Model S-I systems were also investigated to select the optimum basis sets for iodine and correct for basis set superposition error. Structure energy minimizations show more realistic geometries for solution and gas phase systems. Systems with multiple organoiodines bonding to a unique sulfur, a previously unstudied phenomenon, were also modeled. Other effects on the geometries of the solid-state crystal structures include hydrogen bonding forming dimers as well as long ribbons that influence crystal packing.