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Cyanate
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<h2 id="cyanate-ion">Cyanate ion</h2> <p>The three atoms in a cyanate ion lie on a straight line, giving the ion a linear structure. The <a href="/facts/Electronic_structure/RuHwQWfp">electronic structure</a> is described most simply as </p> :Ö̤−C≡N: <p>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 <a href="/facts/Infrared_spectrum/44XdJNcc">infrared spectrum</a> of a cyanate salt has a band at ca. 2096 cm−1; such a high frequency is characteristic of a <a href="/facts/Triple_bond/poDWRayX">triple bond</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p><p>The cyanate ion is a <a href="/facts/Lewis_base/qlLqRvg2">Lewis base</a>. Both the oxygen and nitrogen atoms carry a <a href="/facts/Lone_pair/Q6kEAC4g">lone pair</a> of electrons and either one, the other, or both can be donated to <a href="/facts/Lewis_acid/qlLqRvg2">Lewis acid</a> acceptors. It can be described as an <a href="/facts/Ambidentate_ligand/6etB3qeW">ambidentate ligand</a>. </p> <h2 id="cyanate-salts">Cyanate salts</h2> <p><a href="/facts/Sodium_cyanate/cyS02u0x">Sodium cyanate</a> is <a href="/facts/Isostructural/xWlgsQ95">isostructural</a> with sodium <a href="/facts/Fulminate/EBlo8aXI">fulminate</a>, confirming the linear structure of the cyanate ion.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> It is made industrially by heating a mixture of <a href="/facts/Sodium_carbonate/P6RHvIoK">sodium carbonate</a> and <a href="/facts/Urea/6j84AoCG">urea</a>.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> Na2CO3 + 2 OC(NH2)2 → 2 NaNCO + CO2 + 2 NH3 + H2O <p>A similar reaction is used to make <a href="/facts/Potassium_cyanate/9yPJXksq">potassium cyanate</a>. Cyanates are produced when <a href="/facts/Cyanide/t0o8FMKI">cyanides</a> are oxidized. Use of this fact is made in cyanide decontamination processes where oxidants such as <a href="/facts/Permanganate/nJa04jVh">permanganate</a> and <a href="/facts/Hydrogen_peroxide/vju6HBIc">hydrogen peroxide</a> are used to convert toxic cyanide into less-toxic cyanate. </p> <table><tbody><tr><th>Name</th><th>formula</th><th>Crystal system</th><th>Space group</th><th>Unit cell (Å)</th><th>volume (Å3)</th><th>Density (g/cm3)</th><th>Comment</th><th>Reference</th></tr><tr><td><a href="/facts/Ammonium_cyanate/A0fURmSC">Ammonium cyanate</a></td><td>NH4OCN</td><td>tetragonal</td><td>P4/nmm</td><td><i>a</i>=5.082 <i>b</i>=5.082 <i>c</i>=5.551</td><td></td><td></td><td>decomposes when heated to <a href="/facts/Urea/6j84AoCG">urea</a></td><td><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></td></tr><tr><td>Lithium cyanate</td><td>LiOCN</td><td>trigonal</td><td><i>R</i>3<i>m</i></td><td><i>a</i> = 3.230 <i>b</i> = 14.268 Z=3</td><td>128.90</td><td>1.895</td><td>melts at 475 °C</td><td><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></td></tr><tr><td><a href="/facts/Sodium_cyanate/cyS02u0x">Sodium cyanate</a></td><td>NaOCN</td><td>hexagonal</td><td><i>R</i>3<i>m</i></td><td><i>a</i> = 3.568 <i>c</i> = 15.123</td><td>166.72</td><td>1.94</td><td>melts at 550 °C</td><td><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></td></tr><tr><td><a href="/facts/Potassium_cyanate/9yPJXksq">Potassium cyanate</a></td><td>KOCN</td><td>tetragonal</td><td><i>I</i>4/<i>mcm</i></td><td><i>a</i> = 6.091 <i>c</i> = 7.052</td><td>261.6</td><td>2.056</td><td>melts at 315 °C</td><td><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></td></tr><tr><td>Rubidium cyanate</td><td>RbOCN</td><td>tetragonal</td><td><i>I</i>4/<i>mcm</i></td><td><i>a</i> = 6.35 <i>c</i> = 7.38</td><td>297.58</td><td>2.85</td><td></td><td><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></td></tr><tr><td>Cesium cyanate</td><td>CsOCN</td><td>tetragonal</td><td><i>I</i>4<i>mcm</i></td><td><i>a</i> = 6.519 <i>c</i> = 7.994</td><td>339.68</td><td>3.42</td><td></td><td><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></td></tr><tr><td>Thallium cyanate</td><td>TlOCN</td><td>tetragonal</td><td><i>I</i>4<i>mcm</i></td><td><i>a</i> = 6.23 <i>c</i> = 7.32</td><td>284.3</td><td>5.76</td><td></td><td><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></td></tr><tr><td><a href="/facts/Silver_cyanate/AS1dBK0K">Silver cyanate</a></td><td>AgOCN</td><td>monoclinic</td><td><i>P</i>21/<i>m</i></td><td><i>a</i> = 5.474 <i>b</i> = 6.378 <i>c</i> = 3.417 <i>β</i> = 90.931°</td><td>119.29</td><td>4.173</td><td>melts at 652 °C</td><td><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></td></tr><tr><td>Strontium cyanate</td><td>Sr(OCN)2</td><td>orthorhombic</td><td><i>Fddd</i></td><td><i>a</i> = 6.151 <i>b</i> = 11.268 <i>c</i> = 11.848 Z = 8</td><td>821.1</td><td>2.78</td><td></td><td><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></td></tr></tbody></table> <h2 id="complexes-with-the-cyanate-ion">Complexes with the cyanate ion</h2> <p>Cyanate is an <a href="/facts/Ambidentate_ligand/6etB3qeW">ambidentate ligand</a> which can donate the pair of electrons on the nitrogen atom or the oxygen atom, or both. Structurally the isomers can be distinguished by the geometry of the complex. In <i>N</i>-bonded cyanate complexes the M−NCO unit sometimes has a linear structure, but with <i>O</i>-bonded cyanate the M−O−C unit is bent. Thus, the silver cyanato complex, [Ag(NCO)2]−, has a linear structure as shown by <a href="/facts/X-ray_crystallography/WtI0F5DN">X-ray crystallography</a>.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> However, the crystal structure of <a href="/facts/Silver_cyanate/AS1dBK0K">silver cyanate</a> shows zigzag chains of nitrogen atoms and silver atoms.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> There also exists a structure </p> NCO / \ Ni Ni \ / OCN <p>in which the Ni-N-C group is bent.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p><p><a href="/facts/Infrared_spectroscopy/u1Hzx617">Infrared spectroscopy</a> has been used extensively to distinguish between isomers. Many complexes of <a href="/facts/Divalent/ck7cHByj">divalent</a> metals are <i>N</i>-bonded. <i>O</i>-Bonding has been suggested for complexes of the type [M(OCN)6]<i>n</i>−, M = Mo(III), Re(IV), and Re(V). The yellow complex Rh(<a href="/facts/Triphenylphosphine/nYFNCVcJ">PPh3</a>)3(NCO) and orange complex Rh(<a href="/facts/Triphenylphosphine/nYFNCVcJ">PPh3</a>)3(OCN) are <a href="/facts/Linkage_isomerism/hvRYWJ35">linkage isomers</a> and show differences in their infrared spectra which can be used for diagnosis.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> </p><p>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(<a href="/facts/Ethylene_diamine/VDX8VfFv">En</a>)2](<a href="/facts/Tetraphenylborate/BhcMJjCY">BPh4</a>)2. In this compound both the Ni−N−C unit and Ni−O−C unit are bent, even though in the first case donation is through the nitrogen atom.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> </p> <h2 id="cyanate-functional-group">Cyanate functional group</h2> <p>Compounds that contain the cyanate <a href="/facts/Functional_group/GXkSPsjM">functional group</a>, −O−C≡N, are known as cyanates or <a href="/facts/Cyanate_ester/X6QbKgEM">cyanate esters</a>. <a href="/facts/Aryl/M3z7QRXd">Aryl</a> cyanates such are phenyl cyanate, C6H5OCN can be formed by a reaction of <a href="/facts/Phenol/ACJs5NIU">phenol</a> with <a href="/facts/Cyanogen_chloride/lRwu51A5">cyanogen chloride</a>, ClCN, in the presence of a base. </p><p><a href="/facts/Organic_compound/gqCNaN45">Organic compounds</a> that contain the isocyanate <a href="/facts/Functional_group/GXkSPsjM">functional group</a> −N=C=O are known as <a href="/facts/Isocyanate/YYDoDBgp">isocyanates</a>. It is conventional in <a href="/facts/Organic_chemistry/djxhxaNg">organic chemistry</a> to write isocyanates with two double bonds, which accords with a simplistic <a href="/facts/Valence_bond_theory/F04YPkfJ">valence bond theory</a> of the bonding. In <a href="/facts/Nucleophilic_substitution/MLLeSsnr">nucleophilic substitution</a> reactions cyanate usually forms an isocyanate. Isocyanates are widely used in the manufacture of <a href="/facts/Polyurethane/qNo2KSXA">polyurethane</a><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> products and <a href="/facts/Pesticide/Uhf4KnwJ">pesticides</a>; <a href="/facts/Methyl_isocyanate/N9hgqxLe">methyl isocyanate</a>, used to make pesticides, was a major factor in the <a href="/facts/Bhopal_disaster/VqtcLwtY">Bhopal disaster</a>. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Cyanide/t0o8FMKI">Cyanide</a>, CN− and <a href="/facts/Nitrile/Gz7RCnC6">nitrile</a> group, −C≡N</li> <li><a href="/facts/Isocyanide/VmkIBMKR">Isocyanide</a> or isonitrile group, −N≡C</li> <li><a href="/facts/Thiocyanate/S438CJp8">Thiocyanate</a>, SCN−, −S−C≡N</li> <li><a href="/facts/Selenocyanate/jvvTfbz0">Selenocyanate</a>, SeCN−, −Se−C≡N</li> <li>Tellurocyanate, TeCN−, −Te−C≡N</li> <li><a href="/facts/Isocyanate/YYDoDBgp">Isocyanate</a> group, −N=C=O</li> <li><a href="/facts/Isothiocyanate/zk3Q3Pv8">Isothiocyanate</a> group, −N=C=S</li> <li>Isoselenocyanate group, −N=C=Se</li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://www.fishersci.com/store/msds?partNumber=AC201111000&countryCode=US&language=en">Material Safety Data Sheet for potassium cyanate</a></li></ul> <h2 id="bibliography">Bibliography</h2> <ul><li><a href="/facts/Norman_Greenwood/XRDmRE8L">Greenwood, Norman N.</a>; Earnshaw, Alan (1997). <i>Chemistry of the Elements</i> (2nd ed.). <a href="/facts/Butterworth-Heinemann/c9nUxIVF">Butterworth-Heinemann</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-08-037941-8.</li> <li>Nakamoto, K. (1997). <i>Infrared and Raman spectra of Inorganic and Coordination compounds</i>. Part A (5th ed.). Wiley. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 0-471-16394-5.</li> <li>Nakamoto, K. (1997). <i>Infrared and Raman spectra of Inorganic and Coordination compounds</i>. Part B (5th ed.). Wiley. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 0-471-16392-9.</li> <li>Wells, A.F (1962). <i>Structural Inorganic Chemistry</i> (3rd. ed.). Oxford: Clarendon Press. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 0-19-855125-8.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>William R. Martin and David W. Ball (2019): "Small organic fulminates as high-energy materials. Fulminates of acetylene, ethylene, and allene". Journal of Energetic Materials, volume 31, issue 7, pages 70-79. doi:10.1080/07370652.2018.1531089 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Nakamoto, Part A, p171 <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Wells, p722. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Greenwood, p324 <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>MacLean, Elizabeth J.; Harris, Kenneth D. M.; Kariuki, Benson M.; Kitchin, Simon J.; Tykwinski, Rik R.; Swainson, Ian P.; Dunitz; Jack D. (2003). "Ammonium cyanate shows N-H···N hydrogen bonding, not N-H···O". Journal of the American Chemical Society. 125: 14449–14451. doi:10.1021/ja021156x. PMID 14624593. <a href="/wiki/Jack_Dunitz" target="_blank">/wiki/Jack_Dunitz</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Erik Hennings; Horst Schmidt; Wolfgang Voigt (2011). "Structure and Thermal Properties of Lithium Cyanate". Zeitschrift für anorganische und allgemeine Chemie. 637 (9): 1199–1202. doi:10.1002/zaac.201100081. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Olaf Reckeweg; Armin Schulz; Brian Leonard; Francis J. DiSalvo (2010). "Single-Crystal X-Ray Diffraction Study of Na[OCN] at 170 K and its Vibrational Spectra". Zeitschrift für Naturforschung B. 65 (4): 528–532. doi:10.1515/znb-2010-0416. <a href="https://doi.org/10.1515%2Fznb-2010-0416" target="_blank">https://doi.org/10.1515%2Fznb-2010-0416</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Hiroki Nambu; Mizuhiko Ichikawa; Torbjörn Gustafsson; Ivar Olovsson (2003). "X-ray diffraction study of KOCN at room temperature". Journal of Physics and Chemistry of Solids. 64 (11): 2269–2272. doi:10.1016/S0022-3697(03)00258-0. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>T. C. Waddington "Lattice parameters and infrared spectra of some inorganic cyanates" J. Chem. Soc., 1959, 2499-2502. doi:10.1039/JR9590002499 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Olaf Reckeweg; Armin Schulz; Francis J. DiSalvo (2020). "Structural characterization and Raman spectrum of Cs[OCN]". Zeitschrift für Naturforschung B. 75 (1–2): 129–133. doi:10.1515/znb-2019-0168. <a href="https://doi.org/10.1515%2Fznb-2019-0168" target="_blank">https://doi.org/10.1515%2Fznb-2019-0168</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>T. C. Waddington "Lattice parameters and infrared spectra of some inorganic cyanates" J. Chem. Soc., 1959, 2499-2502. doi:10.1039/JR9590002499 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>D.J. Williams; S.C. Vogel; L.L. Daemen (2006). "Neutron diffraction study of cyanate ligand order/disorder in AgNCO at 300–50K". Physica B: Condensed Matter. 385–386 (1): 228–230. doi:10.1016/j.physb.2006.05.197. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Sandro Pagano; Giuseppe Montana; Claudia Wickleder; Wolfgang Schnick (2009). "Urea Route to Homoleptic Cyanates—Characterization and Luminescence Properties of [M(OCN)2(urea)] and M(OCN)2 with M=Sr, Eu". Chemistry: A European Journal. 15 (25): 6186–6193. doi:10.1002/chem.200900053. PMID 19444832. <a href="https://doi.org/10.1002%2Fchem.200900053" target="_blank">https://doi.org/10.1002%2Fchem.200900053</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 325. ISBN 978-0-08-037941-8. (click here) <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Britton, D.; Dunitz, J. D. (1965). "The crystal structure of silver cyanate". Acta Crystallographica. 18 (3): 424–428. doi:10.1107/S0365110X65000944. <a href="https://scripts.iucr.org/cgi-bin/paper?a04540" target="_blank">https://scripts.iucr.org/cgi-bin/paper?a04540</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 325. ISBN 978-0-08-037941-8. (click here) <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Nakamoto, Part B, pp 121–123. <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Greenwood, Table 8.9 <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Seymour, Raymond B.; Kauffman, George B. (1992). "Polyurethanes: A Class of Modern Versatile Materials". J. Chem. Educ. 69 (11): 909. Bibcode:1992JChEd..69..909S. doi:10.1021/ed069p909. <a href="/wiki/George_B._Kauffman" target="_blank">/wiki/George_B._Kauffman</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> </ol>