heptasulfur imide
{{Chembox
| ImageFile = S7NHstructurePlanarN.png
| ImageSize =
| ImageAlt = Skeletal formula of heptasulfur imide
| ImageFile1 = Heptasulfur imide molecule ball.png
| ImageSize1 = 150
| ImageAlt1 = Ball-and-stick model of the heptasulfur imide molecule
| IUPACName = Heptathiazocanehttps://pubchem.ncbi.nlm.nih.gov/compound/3446506#section=IUPAC-Name&fullscreen=true
| OtherNames = {{ubl|Azacyclooctasulfane|Heptasulfur imide}}
|Section1={{Chembox Identifiers
| CASNo = 293-42-5
| PubChem = 3446506
| ChemSpiderID = 2689062
| SMILES = N1SSSSSSS1
| StdInChI = 1S/HNS7/c1-2-4-6-8-7-5-3-1/h1H
| StdInChIKey = NLDXLSSPVWXKBF-UHFFFAOYSA-N}}
|Section2={{Chembox Properties
| Formula = {{chem2|S7NH}}
| S=7|N=1|H=1
| Appearance = Pale yellow solid
| Density = 2.01 g/cm3
| MeltingPtC = 113.5
| BoilingPt =
| Solubility = }}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
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Heptasulfur imide is the inorganic compound with the formula {{chem2|S7NH|auto=1}}. 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) {{chem2|S_{x}(NH)_{y}|}}.
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. {{doi|10.1002/9780470132395.ch26}} although other methods have been developed.Bojes, J.; Chivers, T.; Drummond, I. "Heptathiazocine(heptasulfurimide) and tetrabutylammonium tetrathionitrate" Inorganic Syntheses (1978), 18, 203-6. {{doi|10.1002/9780470132494.ch36}} Together with {{chem2|S7NH}}, the reaction also produces three isomers (1,3-{{chem2|S6(NH)2}}, 1,4-{{chem2|S6(NH)2}} and 1,5-{{chem2|S6(NH)2}}) of {{chem2|S6(NH)2}} (diazacyclooctasulfanes) and two isomers (1,3,5-{{chem2|S5(NH)3}} and 1,3,6-{{chem2|S5(NH)3}}) of {{chem2|S5(NH)3}} (triazacyclooctasulfanes).{{Cite book |last=Greenwood |first=Norman Neill |title=Chemistry of the elements |last2=Earnshaw |first2=Alan |date=1997 |publisher=Butterworth-Heinemann |isbn=978-0-7506-3365-9 |edition=2nd |location=Oxford Auckland Boston [etc.]}}
Azacyclooctasulfane is an analogue of octasulfur (cyclooctasulfane) {{chem2|S8}}, with one {{chem2|\sS\s}} replaced by {{chem2|\sNH\s}}. The {{chem2|S\sNH\sS}} 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. {{doi|10.1002/zaac.19764260106}} suggesting that the amine is nonbasic.