Thiocyanic acid is a chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with the formula HSCN that exists as a mixture with the isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

ic compound isothiocyanic acid (HNCS). It is the sulfur analog of cyanic acid (HOCN).

It is a weak acid, bordering on strong, with a pKa of 1.1 at 20°C and extrapolated to zero ionic strength.

HSCN is predicted to have a triple bond

Triple bond

A triple bond in chemistry is a chemical bond between two chemical elements involving six bonding electrons instead of the usual two in a covalent single bond. The most common triple bond, that between two carbon atoms, can be found in alkynes. Other functional groups containing a triple bond are...

 between carbon and nitrogen. It has been observed spectroscopically but has not been isolated as a pure substance.

The salts and ester

Ester

Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

s of thiocyanic acid are known as thiocyanate

Thiocyanate

Thiocyanate is the anion [SCN]−. It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Organic compounds containing the functional group SCN are also called thiocyanates...

s. The salts are composed of the thiocyanate ion (^-SCN) and a suitable metal cation (e.g., potassium thiocyanate

Potassium thiocyanate

Potassium thiocyanate is the chemical compound with the molecular formula KSCN. It is an important salt of the thiocyanate anion, one of the pseudohalides...

, KSCN). The esters of thiocyanic acid have the general structure R-SCN.