Thiocyanate


Thiocyanate

Thiocyanate (also known as sulphocyanate or thiocyanide or rhodanide) is the anion, [SCN] . Common compounds include the colourless salts potassium thiocyanate and sodium thiocyanate. Organic compounds containing the functional group SCN are also called thiocyanates. Mercury(II) thiocyanate was formerly used in pyrotechnics.

Thiocyanate is analogous to the cyanate ion, [OCN] , where in oxygen is replaced by sulfur. [SCN] is one of the pseudohalides, due to the similarity of its reactions to that of halide ions. Thiocyanate was formerly known as rhodanide (from a Greek word for rose) because of the red colour of its complexes with iron. Thiocyanate is produced by the reaction of elemental sulfur or thiosulfate with cyanide:: 8 CN + S8 → 8 SCN: CN + S2O32− → SCN + SO32−The latter reaction is catalyzed by the enzyme sulfotransferase known as rhodanase and may be relevant to detoxification of cyanide in the body.

tructure, bonding and coordination chemistry

Thiocyanate shares its negative charge approximately equally between sulfur and nitrogen. Consequently, thiocyanate can act as a nucleophile at either sulfur or nitrogen — it is an ambidentate ligand. [SCN] can also bridge two (M−SCN−M) or even three metals (>SCN− or −SCN<). Experimental evidence leads to the general conclusion that class a metals (hard acids) tend to form "N"-bonded thiocyanate complexes, whereas class b metals (soft acids) tend to form "S"-bonded thiocyanate complexes. Other factors, e.g. kinetics and solubility, are sometimes involved, and linkage isomerism can occur, for example [Co(NH3)5(NCS)] Cl2 and [Co(NH3)5(SCN)] Cl2Greenwood&Earnshaw p. 326] .

Organic thiocyanates

Organic and transition metal derivatives of the thiocyanate ion can exist as "linkage isomers." In thiocyanates, the organic group or metal is attached to sulfur: R−S−C≡N has a S-C single bond and a C-N triple bond [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] . In isothiocyanates, the substituent is attached to nitrogen: R−N=C=S has a S-C double bond and a C-N double bondOrganic thiocyanates are hydrolyzed to thiocarbamates in the Riemschneider thiocarbamate synthesis.

Test for iron(III)

If [SCN] is added to a solution containing iron(III) ions (Fe3+), a blood red solution is formed due to the presence of the [Fe(NCS)(H2O)5] 2+.

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • thiocyanate — ● thiocyanate nom masculin Sel ou ester de l acide thiocyanique. ● thiocyanate (synonymes) nom masculin Sel ou ester de l acide thiocyanique. Synonymes : sulfocyanate …   Encyclopédie Universelle

  • Thiocyanate — Thi o*cy a*nate, n. (Chem.) Same as {Sulphocyanate}. [1913 Webster] …   The Collaborative International Dictionary of English

  • thiocyanate — [thī΄ōsī′ə nāt΄] n. 1. a salt of thiocyanic acid containing the monovalent, negative radical SCN 2. an uncharged ester of this acid …   English World dictionary

  • Thiocyanate — L anion thiocyanate Les thiocyanates aussi connus sous les noms de sulphocyanates, thiocyanures et rhodanures[1] sont des composés intégrant l anion [SCN]− qui est la base conjuguée de l acide thiocyanique (HSCN). Les sels incolores …   Wikipédia en Français

  • Thiocyanate — Thiocyanat Anion Als Thiocyanate (veraltet auch Rhodanide) werden die Salze und die Ester der unbeständigen Thiocyansäure (Rhodanwasserstoffsäure) HSCN bezeichnet. Der Name „Rhodanid“ leitet sich von griechisch rhodos für rot ab, da Eisen(III)… …   Deutsch Wikipedia

  • thiocyanate — Sulphocyanate Sul pho*cy a*nate, n. (Chem.) A salt of sulphocyanic acid; also called {thiocyanate}, and formerly inaccurately {sulphocyanide}. [1913 Webster] {Ferric sulphocyanate} (Chem.), a dark red crystalline substance usually obtained in a… …   The Collaborative International Dictionary of English

  • thiocyanate — /thuy oh suy euh nayt /, n. Chem. a salt or ester of thiocyanic acid, as sodium thiocyanate, NaSCN. Also, thiocyanide /thuy oh suy euh nuyd /. [1875 80; THIO + CYANATE] * * * …   Universalium

  • thiocyanate — A salt of thiocyanic acid. SYN: rhodanate, sulfocyanate. * * * thio·cy·a·nate .thī ō sī ə .nāt, nət n a compound that consists of the chemical group SCN bonded by the sulfur atom to a group or an atom other than a hydrogen atom * * *… …   Medical dictionary

  • thiocyanate — noun Etymology: International Scientific Vocabulary Date: 1877 a compound that consists of the chemical group SCN bonded by the sulfur atom to a group or an atom other than a hydrogen atom …   New Collegiate Dictionary

  • thiocyanate — noun any salt or ester of thiocyanic acid; or the SCN radical or the SCN anion …   Wiktionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.