Trithiazyl trichloride

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.

Trithiazyl trichloride

Names
Other names thionitrosyl chloride
Identifiers
CAS Number	trimer: 5964-00-1 monomer: 17178-58-4
3D model (JSmol)	trimer: Interactive image monomer: Interactive image
ChemSpider	trimer: 9271996 monomer: 123637
PubChem CID	trimer: 11096854 monomer: 140196
CompTox Dashboard (EPA)	trimer: DTXSID801337169 monomer: DTXSID70938043
InChI InChI=1S/Cl3N3S3/c1-7-4-8(2)6-9(3)5-7 Key: QBQMTUMJJWPFDJ-UHFFFAOYSA-N monomer: InChI=1S/ClNS/c1-3-2 Key: FWVIYFTZAHMHIO-UHFFFAOYSA-N
SMILES trimer: ClS1=NS(Cl)=NS(Cl)=N1 monomer: N#SCl
Properties
Chemical formula	(NSCl)3
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). Infobox references

Structure

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 C_3v 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

Trithiazyl trichloride is obtained by chlorination of tetrasulfur tetranitride or thiazyl fluoride monomer:^[4]

3 S₄N₄ + 6 Cl₂ → 4 (NSCl)₃

3 FSN + 3 Cl₂ → (NSCl)₃ + 3 ClF

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.

Alkoxide or silver salts displace the chlorides:^[5]

(-NS(Cl)-)₃ + 3 NaOR → (-NS(OR)-)₃ + 3 NaCl

(-NS(Cl)-)₃ + 3 AgX → (-NS(X)-)₃ + 3 AgCl

Treating thiazyl chloride with sulfur in the presence of antimony pentachloride gives dithionitronium hexachloroantimonate:^[6]

SNCl + S + SbCl₅ → [NS₂]SbCl₆

It reacts with nitriles to dithiadiazolium chlorides:^[2]

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

Sulfur trioxide successively oxidizes the compound at the sulfur atoms to (NSOCl)₃,^[4] which exists as stereoisomers.