Dithionitronium hexafluoroarsenate

Dithionitronium hexafloroarsenate is the inorganic compound with the formula [SN₂]AsF₆. It is the hexafluoroarsenate (AsF−6) salt of S=N=S⁺. The cation is of interest as the sulfur analogue of nitronium (NO+2). Hexafloroarsenate is a weakly coordinating anion. According to X-ray crystallography, S=N=S⁺ is linear with S-N distances of 146 picometers.^[1]

Dithionitronium hexafluoroarsenate

Identifiers
CAS Number	80485-40-1
3D model (JSmol)	Interactive image
ChemSpider	9509584
PubChem CID	11334638
InChI InChI=1S/AsF6.NS2/c2-1(3,4,5,6)7;2-1-3/q-1;+1 Key: FHQHPTGLQAUWCS-UHFFFAOYSA-N
SMILES [N+](=S)=S.F[As-](F)(F)(F)(F)F
Properties
Chemical formula	AsF6N2S
Molar mass	248.99 g·mol−1
Appearance	yellow solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis and reactions

Dithionitronium hexafluoroarsenate is prepared from thiazyl chloride using silver hexafluoroarsenate.^[2] The hexachloroantimonate salt can be prepared by treating thiazyl chloride with sulfur in the presence of antimony pentachloride according to this idealized equation:

SNCl + S + SbCl₅ → [NS₂]SbCl₆

The dithionitronium cation reacts with nitriles to give dithiadiazolium salts:^[3]

[NS₂]⁺ + RCN → [RCN₂S₂]⁺

Addition to alkynes gives dithiazolium salts:

[NS₂]⁺ + R₂C₂ → [(RC)₂NS₂]⁺