Trithiazyl trichloride

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Trithiazyl trichloride
Other names
thionitrosyl chloride
3D model (JSmol)
  • InChI=1S/Cl3N3S3/c1-7-4-8(2)6-9(3)5-7
  • monomer: InChI=1S/ClNS/c1-3-2
  • trimer: ClS1=NS(Cl)=NS(Cl)=N1
  • monomer: N#SCl
Molar mass 244.55 g·mol−1
Appearance white solid
Melting point 168 °C (334 °F; 441 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Trithiazyl trichloride is the inorganic compound with the formula (NSCl)3. A white solid, it is a precursor to other sulfur nitrides,[1] but has no commercial applications.


The molecule is a 6-membered ring of alternating nitrogen and sulfur atoms, where each sulfur atom is attached to one chlorine atom by a single bond. The molecule contains alternating single and double bonds in the S3N3 core. The molecule has C3v symmetry. The S3N3 core is slightly ruffled structure with S-N distances of 160.5 pm. The S-Cl distances are 208 pm, and the chlorine atoms are mutually cis. The S centers are tetravalent and pyramidal. In contrast to the NSCl connectivity, nitrosyl chloride has the connectivity ONCl.[2][3]

Synthesis and reactions[edit]

Trithiazyl trichloride is obtained by chlorination of tetrasulfur tetranitride:

3 S4N4 + 6 Cl2 → 4 (NSCl)3

At 100 °C in vacuum, thiazyl chloride trimer undergoes cracking to thiazyl chloride monomer, which is a green gas.

(−N=S(−Cl)−)3 → 3 N≡S−Cl

In N≡S−Cl, chlorine is bonded to sulfur, in contrast to nitrosyl chloride O=N–Cl, where chlorine is bonded to nitrogen. In contrast, with six fewer electrons, cyanuric chloride is a planar ring.

It reacts with nitriles to dithiadiazolium chlorides:[2]

6 RCN + 4 (NSCl)3 → 6 [RCN2S2]+Cl + 3 Cl2 + 3 N2

The compound oxidizes to the S(VI) compound (NSOCl)3, which exists as isomers.


  1. ^ William L. Jolly, Keith D. Maguire (1967). "Sulfur Nitrogen Chlorides". Inorganic Syntheses. Inorg. Synth. Inorganic Syntheses. Vol. IX. p. 102. doi:10.1002/9780470132401.ch27. ISBN 9780470132401.{{cite book}}: CS1 maint: uses authors parameter (link)
  2. ^ a b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  3. ^ Wiegers, G. A.; Vos, A. (1966). "The Crystal Structures of Two Sulfur-Nitrogen Compounds with (S-N)3 Rings. II. Trithiazylchloride, (NSCl)3, at -130 C". Acta Crystallographica. 20 (2): 192. doi:10.1107/s0365110x66000410.{{cite journal}}: CS1 maint: uses authors parameter (link)