Heptasulfur imide

Heptasulfur imide is the inorganic compound with the formula S₇NH. 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) S_x(NH)_y.

Heptasulfur imide

Names
IUPAC name Heptathiazocane[1]
Other names Azacyclooctasulfane Heptasulfur imide
Identifiers
CAS Number	293-42-5
3D model (JSmol)	Interactive image
ChemSpider	2689062
PubChem CID	3446506
CompTox Dashboard (EPA)	DTXSID70392545
InChI InChI=1S/HNS7/c1-2-4-6-8-7-5-3-1/h1H Key: NLDXLSSPVWXKBF-UHFFFAOYSA-N
SMILES N1SSSSSSS1
Properties
Chemical formula	S7NH
Molar mass	239.44 g·mol−1
Appearance	Pale yellow solid
Density	2.01 g/cm3
Melting point	113.5 °C (236.3 °F; 386.6 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis and structure

It is prepared by reaction of disulfur dichloride with ammonia,^[2] although other methods have been developed.^[3] Together with S₇NH, the reaction also produces three isomers (1,3-S₆(NH)₂, 1,4-S₆(NH)₂ and 1,5-S₆(NH)₂) of S₆(NH)₂ (diazacyclooctasulfanes) and two isomers (1,3,5-S₅(NH)₃ and 1,3,6-S₅(NH)₃) of S₅(NH)₃ (triazacyclooctasulfanes).^[4]

Azacyclooctasulfane is an analogue of octasulfur (cyclooctasulfane) S₈, with one −S− replaced by −NH−. The S−NH−S center is almost planar,^[5] suggesting that the amine is nonbasic.