Further structural motifs from the reactions of thioamides with diiodine and the interhalogens iodine monobromide and iodine monochloride: an FT-Raman and crystallographic study †

Abstract

The reactions of the thioamides thiourea, tu, 1-ethyl-2-thiourea, etu, 1,3-dimethyl-2-thiourea, dmtu, 1,3-diethyl-2-thiourea, detu, 3-methylbenzothiazole-2-thione, mbtt and 3-methylrhodanine, mrh, with one equivalent of diiodine have been studied; attempts have been made to characterise the resultant 1∶1 addition products using FT-Raman spectroscopy. It has been shown that these materials lie on a CT–ionic borderline. The crystal structure of dmtu·I2 has been determined and is shown to be ionic and of the form [(dmtu)2I]+I3−, an arrangement previously only rarely found in crystallographic reports. The reactions of etu and dmtu with iodine monobromide and iodine monochloride and of mbtt with iodine monobromide give 1∶1 interhalogen addition products; initial FT-Raman investigations point to these adopting a CT ‘spoke’ structure. The reaction of tu with two equivalents of diiodine to give a bulk material of stoichiometry tu·I4 has been studied in detail and shown to lead to a variety of novel polyiodide arrangements, the crystal structures of two of which are reported, (tu)2(I2)3 and (tu)3(I2)5, and compared to each other, the previously reported (tu)2I2 and to tu itself. These two structures represent further, previously unreported, structural motifs available for these highly complicated systems.