Thiocyanogen

Thiocyanogen

200px
200px
200px
Identifiers
CAS Number	505-14-6 N
ChEBI	CHEBI:30063 Y
ChemSpider	61468 Y
Jmol 3D model	Interactive image
PubChem	68160
InChI InChI=1S/C2N2S2/c3-1-5-6-2-4 Y Key: DTMHTVJOHYTUHE-UHFFFAOYSA-N Y InChI=1/C2N2S2/c3-1-5-6-2-4 Key: DTMHTVJOHYTUHE-UHFFFAOYAE
SMILES N#CSSC#N
Properties
Chemical formula	C2N2S2
Molar mass	116.16 g mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Thiocyanogen, (SCN)₂, is a pseudohalogen derived from the pseudohalide thiocyanate, [SCN]⁻. This hexatomic compound exhibits C₂ point group symmetry and has the connectivity NCS-SCN. The oxidation ability is greater than bromine. It reacts with water:

(SCN)₂ + H₂O → HSCN + HSCNO

Thiocyanogen was originally prepared by the reaction of iodine with a suspension of silver thiocyanate in diethyl ether, but this reaction suffers from competing equilibria attributed to the weak oxidizing power of iodine. An improved method for generating thiocyanogen entails oxidation of plumbous thiocyanate, which precipitates when aqueous solutions of lead(II) nitrate and sodium thiocyanate are combined. A suspension of anhydrous Pb(SCN)₂ is treated with bromine in glacial acetic acid to afford a 0.1M solution of thiocyanogen that is stable for days. Alternatively, a solution of bromine in methylene chloride is added dropwise to a suspension of Pb(SCN)₂ in methylene chloride at 0 °C followed by filtration under argon to give a solution of thiocyanogen that should be used immediately.

Pb(SCN)₂ + Br₂ → (SCN)₂ + PbBr₂

Thiocyanogen adds to alkenes to give 1,2-bis(thiocyanato) compounds and reacts with titanacyclopentadienes giving (Z,Z)-1,4-bis(thiocyanato)-1,3-butadienes, which in turn can be converted to 1,2-dithiins. Selenocyanogen, (SeCN)₂, prepared from reaction of silver selenocyanate with iodine in tetrahydrofuran at 0 °C, reacts in a similar manner to thiocyanogen.