Thiocyanate (also known as sulphocyanate or thiocyanide) is both an anion SCN^- and, in organic chemistry, a functional group:

An example of the anion is found in potassium thiocyanate, KSCN.

Thiocyanate is analogous to the cyanate ion, OCN^-, wherein oxygen is replaced by sulfur. SCN^- is one of the pseudo-halogens, due to the similarity of its reactivity with halogen ions. Thiocyanate was formerly known as rhodanide (from a Greek word for rose) because of the red colour of its iron derivatives. Thiocyanates are typically colorless.

Organic and transition metal derivatives can exist as linkage isomers: In thiocyanates, the organic group or metal is attached to sulfur. An example include PhSCN, phenylthiocyanate. In this case a triple bond between C and N is indicated. In isothiocyanates, the substituent is attached to nitrogen. An example is PhNCS. In this case double bonds are indicated, i.e. Ph-N=C=S.

Thiocyanate is produced by the reaction of elemental sulfur with cyanide:

8 CN^- + S₈ → 8 SCN^-

In some organisms cyanide is detoxified by this conversion as catalyzed by the enzyme sulfotransferase known as rhodanese.

Guy, R. G. "Syntheses and Preparative Applications of Thiocyanates" in "Chemistry of Cyanates and Their Derivatives," vol II. Patai, S., (Editor), John Wiley, 1977. New York

Uses of thiocyanate ion

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Test for Iron(III)

If $SCN^-$ is added to a solution containing Iron(III) ions, a blood red solution is formed due to the presence of the $*^\{2+\}$ complex.

External links

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functional groups | Cyanates | Thiocyanates

Thiocyanate