Sulfur atoms are an effective partner for halogen atoms in the formation of halogen bonds. Localized nucleophilic regions occurring on sulfur (or other chalcogen) atoms can form electrostatically attractive interactions with localized electrophilic regions occurring on halogen atoms to form relatively strong noncovalent interactions. The current study seeks to develop crystal engineering principles surrounding these interactions by synthesizing new cocrystal compositions and evaluating the resulting halogen bond motifs and strength. In this vein several new thioimidazoles have been synthesized and their halogen bonding capabilities evaluated through the synthesis of thioimidazole-organoiodine cocrystals. Various functional groups were added to the thioimidazole core, occurring on the thioimidazole nitrogen atoms as well as the carbon atoms of the thioimidazole ring. This provided a variety of sulfur-containing substrates to systematically evaluate with organoiodine molecules including 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene, 1,3,5- triiodo-2,4-6-trifluorobenzene, tetraiodoethylene, and I2. A variety of I···S interactions were characterized via single crystal X-ray diffraction. In particular, the addition of chloro- and nitro- substituents to a dimethylimidazole thione substrate provided the additional opportunity to study the halogen bonding tendencies in systems where I···S, I···Cl, or I···O interactions could potentially occur in concert or in competition. Organoiodine Cocrystals with Novel Thiones
WITH MERIDEE RITZER, FATEMA TUZ ZOHARA, JULIA L. BRUMAGHIM, COLIN D. MCMILLEN, AND
DR. WILLIAM T. PENNINGTON, DEPARTMENT OF CHEMISTRY
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