Cyanate
The cyanate ion is an
of three forms: [O−−C≡N] (61%) ↔ [O=C=N−] (30%) ↔ [O+≡C−N2−] (4%).Cyanate is the derived anion of isocyanic acid, H−N=C=O, and its lesser tautomer cyanic acid (a.k.a. cyanol), H−O−C≡N.
Any salt containing the ion, such as ammonium cyanate, is called a cyanate.
The cyanate ion is an isomer of the much-less-stable fulminate anion, CNO− or [C−≡N+−O−].[1]
The cyanate ion is an
Compounds that contain the cyanate
Cyanate ion
The three atoms in a cyanate ion lie on a straight line, giving the ion a linear structure. The
- :Ö̤−C≡N:
with a single C−O bond and a triple C≡N bond. (Or more completely as :Ö̤−C≡N: ↔ Ö̤=C=N̤̈ ↔ :O≡C−N̤̈:) The
The cyanate ion is a
Cyanate salts
Sodium cyanate is isostructural with sodium fulminate, confirming the linear structure of the cyanate ion.[3] It is made industrially by heating a mixture of sodium carbonate and urea.[4]
- Na2CO3 + 2 OC(NH2)2 → 2 NaNCO + CO2 + 2 NH3 + H2O
A similar reaction is used to make potassium cyanate. Cyanates are produced when cyanides are oxidized. Use of this fact is made in cyanide decontamination processes where oxidants such as permanganate and hydrogen peroxide are used to convert toxic cyanide into less-toxic cyanate.
Name | formula | Crystal system | Space group | Unit cell (Å) | volume (Å3) | Density (g/cm3) | Comment | Reference |
---|---|---|---|---|---|---|---|---|
Ammonium cyanate | NH4OCN | tetragonal | P4/nmm | a=5.082 b=5.082 c=5.551 | decomposes when heated to urea | [5] | ||
Lithium cyanate | LiOCN | trigonal | R3m | a = 3.230 b = 14.268 Z=3 | 128.90 | 1.895 | melts at 475 °C | [6] |
Sodium cyanate | NaOCN | hexagonal | R3m | a = 3.568 c = 15.123 | 166.72 | 1.94 | melts at 550 °C | [7] |
Potassium cyanate | KOCN | tetragonal | I4/mcm | a = 6.091 c = 7.052 | 261.6 | 2.056 | melts at 315 °C | [8] |
Rubidium cyanate | RbOCN | tetragonal | I4/mcm | a = 6.35 c = 7.38 | 297.58 | 2.85 | [9] | |
Cesium cyanate | CsOCN | tetragonal | I4mcm | a = 6.519 c = 7.994 | 339.68 | 3.42 | [10] | |
Thallium cyanate | TlOCN | tetragonal | I4mcm | a = 6.23 c = 7.32 | 284.3 | 5.76 | [9] | |
Silver cyanate | AgOCN | monoclinic | P21/m | a = 5.474 b = 6.378 c = 3.417 β = 90.931° | 119.29 | 4.173 | melts at 652 °C | [11] |
Strontium cyanate | Sr(OCN)2 | orthorhombic | Fddd | a = 6.151 b = 11.268 c = 11.848 Z = 8 | 821.1 | 2.78 | [12] |
Complexes with the cyanate ion
Cyanate is an
NCO / \ Ni Ni \ / OCN
in which the Ni-N-C group is bent.[13]
The cyanate ion can bridge between two metal atoms by using both its donor atoms. For example, this structure is found in the compound [Ni2(NCO)2(
Cyanate functional group
Compounds that contain the cyanate
Organic compounds that contain the isocyanate functional group −N=C=O are known as isocyanates. It is conventional in organic chemistry to write isocyanates with two double bonds, which accords with a simplistic valence bond theory of the bonding. In nucleophilic substitution reactions cyanate usually forms an isocyanate. Isocyanates are widely used in the manufacture of polyurethane[17] products and pesticides; methyl isocyanate, used to make pesticides, was a major factor in the Bhopal disaster.
See also
- Cyanide, CN− and nitrile group, −C≡N
- Isocyanide or isonitrile group, −N≡C
- Thiocyanate, SCN−, −S−C≡N
- Selenocyanate, SeCN−, −Se−C≡N
- Tellurocyanate, TeCN−, −Te−C≡N
- Isocyanate group, −N=C=O
- Isothiocyanate group, −N=C=S
- Isoselenocyanate group, −N=C=Se
References
External links
Bibliography
- ISBN 978-0-08-037941-8.
- Nakamoto, K. (1997). Infrared and Raman spectra of Inorganic and Coordination compounds. Part A (5th ed.). Wiley. ISBN 0-471-16394-5.
- Nakamoto, K. (1997). Infrared and Raman spectra of Inorganic and Coordination compounds. Part B (5th ed.). Wiley. ISBN 0-471-16392-9.
- Wells, A.F (1962). Structural Inorganic Chemistry (3rd. ed.). Oxford: Clarendon Press. ISBN 0-19-855125-8.