Thiocyanogen

Chembox new
ImageFile = Thiocyanogen-2D.png ImageSize =
ImageFile1 = Thiocyanogen-3D-balls.png ImageSize1 =
ImageFile2 = Thiocyanogen-3D-vdW.png ImageSize2 =
IUPACName =
OtherNames =
Section1 = Chembox Identifiers
CASNo = 505-14-6
Section2 = Chembox Properties
Formula = C₂N₂S_{2
MolarMass = 116.16 g mol⁻¹
Appearance =
Density =
MeltingPt =
BoilingPt =
Solubility =}

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 [cite journal | first = James | last = Jensen | year = 2005 | title = Vibrational frequencies and structural determination of thiocyanogen | journal = | volume = 714 | issue = 2-3 | pages = 137–141 | doi = 10.1016/j.theochem.2004.09.046 ] . It is attacked by water and apparently has only been obtained as a solution.

Thiocyanogen was originally prepared by the reaction of iodine with a suspension of silver thiocyanate in diethyl ether, [cite journal | last = Söderbäck | first = Erik | year = 1919 | title = Studien über das freie Rhodan | journal = Justus Liebig's Annalen der Chemie | volume = 419 | pages = 217–322 | doi = 10.1002/jlac.19194190302 ] 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. [cite journal | last = Gardner | first = William Howlett | coauthors = Weinberger, Harold | year = 1939 | title = Thiocyanogen Solution | journal = Inorganic Syntheses | volume = 1 | pages = 84–86 | doi = 10.1002/9780470132326.ch29]

:Pb(SCN)₂ + Br₂ → (SCN)₂ + PbBr₂Thiocyanogen adds to alkenes to give 1,2-bis(thiocyanato) compounds.

References