The reaction of thiourea and 1,3-dimethylthiourea towards organoiodines: oxidative bond formation and halogen bonding

Abstract

By varying the halogen-bond-donor molecule, 11 new halogen-bonding cocrystals involving thiourea or 1,3-dimethylthiourea were obtained, namely, 1,3-dimethylthiourea–1,2-diiodo-3,4,5,6-tetrafluorobenzene (1/1), C6F4I2·C3H8N2S, 1, thiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), C6F4I2·CH4N2S, 2, 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), C6F4I2·C3H8N2S, 3, 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene–methanol (1/1/1), C6F4I2·C3H8N2S·CH4O, 4, 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene–ethanol (1/1/1), C6F4I2·C3H8N2S·C2H6O, 5, 1,3-dimethylthiourea–1,4-diiodo-2,3,5,6-tetrafluorobenzene (1/1), C6F4I2·C3H8N2S, 6, 1,3-dimethylthiourea–1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C6F3I3·C3H8N2S, 7, 1,3-dimethylthiourea–1,1,2,2-tetraiodoethene (1/1), C6H16N4S2·C2I4, 8, [(dimethylamino)methylidene](1,2,2-triiodoethenyl)sulfonium iodide–1,1,2,2-tetraiodoethene–acetone (1/1/1), C5H8I3N2S+·I−·C3H6O·C2I4, 9, 2-amino-4-methyl-1,3-thiazol-3-ium iodide–1,1,2,2-tetraiodoethene (2/3), 2C4H7N2S+·2I−·3C2I4, 10, and 4,4-dimethyl-4H-1,3,5-thiadiazine-3,5-diium diiodide–1,1,2,2-tetraiodoethene (2/3), 2C5H12N4S2+·4I−·3C2I4, 11. When utilizing the common halogen-bond-donor molecules 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene, as well as 1,3,5-trifluoro-2,4,6-triiodobenzene, bifurcated I...S...I interactions were observed, resulting in the formation of isolated rings, chains, and sheets. Tetraiodoethylene (TIE) provided I...S...I cocrystals as well, but further yielded a sulfonium-containing product through the reaction of the S atom with TIE. This particular sulfonium motif is the first of its kind to be structurally characterized, and is stabilized in the solid state through a three-dimensional I...I halogen-bonding network. Thiourea reacted with acetone in the presence of TIE to provide two novel heterocyclic products, again stabilized in the solid state through I...I halogen bonding.