Cyanate

Space-filling model of the cyanate anion.

The cyanate ion is an anion consisting of one oxygen atom, one carbon atom, and one nitrogen atom, [OCN]⁻, in that order, and possesses 1 unit of negative charge, borne mainly by the nitrogen atom. In organic compounds the cyanate group is a functional group.

Structure

The structure of cyanate can be considered to be a weighted average of contributions from two canonical forms:

The resonance hybrid resulting from these two contributory structures can be represented as

The cyanate ion is isoelectronic with carbon dioxide, and so shares its linear shape.

The fulminate ion [ONC]⁻ has the same chemical formula but a different structure — it is a structural isomer of cyanate.

Reactions

The cyanate ion is an ambidentate nucleophile in nucleophilic substitution because it can react to form an alkyl cyanate R-OCN (exception) or an alkyl isocyanate R-NCO (rule). Aryl cyanates (C₆H₅OCN) can be formed by a reaction of phenol with cyanogen chloride (ClCN) in the presence of a base.

The cyanate ion is relatively non-toxic in comparison with cyanides. Use of this fact is made in cyanide decontamination processes where oxidants such as permanganate and hydrogen peroxide are used to convert toxic cyanide to safer cyanate.

Cyanates

Cyanates are salts or esters of cyanic acid, for example potassium cyanate (KOCN) or methyl cyanate. See also cyanate ester.