Heptasulfur imide is the inorganic compound with the formula . It is a pale yellow solid that is, like elemental sulfur, highly soluble in carbon disulfide. The compound, which is only of academic interest, is representative of a family of sulfur imides (or azacyclosulfanes or thiacycloazanes) .
Synthesis and structure It is prepared by reaction of disulfur dichloride with ammonia,Becke-Goehring, Margot; Fluck, Ekkehard "Heptasulfur imide" Inorganic Syntheses 1966, vol. 8, 103-5. although other methods have been developed.Bojes, J.; Chivers, T.; Drummond, I. "Heptathiazocine(heptasulfurimide) and tetrabutylammonium tetrathionitrate" Inorganic Syntheses (1978), 18, 203-6. Together with , the reaction also produces three isomers (1,3-, 1,4- and 1,5-) of (diazacyclooctasulfanes) and two isomers (1,3,5- and 1,3,6-) of (triazacyclooctasulfanes).
Azacyclooctasulfane is an analogue of octasulfur (cyclooctasulfane) , with one replaced by . The center is almost planar,Hecht, H. J.; Reinhardt, R.; Steudel, R.; Bradaczek, H. "Redetermination of the crystal and molecular structure of heptasulfur imide, S7NH" Zeitschrift für Anorganische und Allgemeine Chemie 1976, vol. 426, pp. 43-8. suggesting that the amine is nonbasic.
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