# Silver cyanide

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> Source: https://en.wikipedia.org/wiki/Silver_cyanide
> Source revision: 1340230121
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{{chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 470456467
| Name           = Silver cyanide
| ImageFile      = 40_grams_of_silver_cyanide_on_scale.png
| ImageCaption   = 40 grams of silver cyanide on a [scale](/source/Weighing_scale).
| ImageName      = Silver cyanide
| ImageFile1     = Silver-cyanide-xtal-1x1x3-3D-bs-17.png
| ImageCaption1  = Structure of silver cyanide
| IUPACName      = Silver cyanide
| OtherNames     = Argentous cyanide
| Section1       = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10043
| EC_number = 208-048-6
| PubChem = 10475
| UNNumber = 1684
| InChI = 1/CN.Ag/c1-2;/q-1;+1
| InChIKey = LFAGQMCIGQNPJG-UHFFFAOYAM
| SMILES = [C-]#N.[Ag+]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/CN.Ag/c1-2;/q-1;+1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = LFAGQMCIGQNPJG-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 506-64-9
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 33RV6XQ01M
| RTECS = VW3850000
  }}
| Section2       = {{Chembox Properties
| Formula = AgCN
| MolarMass = 133.8856 g/mol
| Appearance = colorless, gray (impure) crystals
| Odor = odorless
| Density = 3.943 g/cm<sup>3</sup>
| Solubility = 0.000023 g/100 mL (20 °C)
| SolubleOther = soluble in concentrated [ammonia](/source/ammonia), boiling [nitric acid](/source/nitric_acid), [ammonium hydroxide](/source/ammonium_hydroxide), [KCN](/source/potassium_cyanide) <br> insoluble in [alcohol](/source/ethanol), dilute [acid](/source/acid)
| SolubilityProduct = 5.97{{e|&minus;17}}<ref name="crc">{{cite book |author1=John Rumble |title=CRC Handbook of Chemistry and Physics |date=June 18, 2018 |publisher=CRC Press |isbn=978-1138561632 |pages=5–189|edition=99 |language=English}}</ref>
| MeltingPtC = 335
| MeltingPt_notes = (decomposes)
| RefractIndex = 1.685
| MagSus = &minus;43.2·10<sup>−6</sup> cm<sup>3</sup>/mol
  }}
| Section3       = {{Chembox Structure
| Coordination = linear
| CrystalStruct = hexagonal
  }}
| Section4       = {{Chembox Thermochemistry
| DeltaHf = 146&nbsp;kJ·mol<sup>−1</sup><ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A23}}</ref>
| Entropy = 84&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup><ref name=b1/>
 }}
| Section7       = {{Chembox Hazards
| ExternalSDS =
| MainHazards = toxic
| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|290|300|310|315|318|330|410}}
| PPhrases = {{P-phrases|234|260|262|264|270|271|273|280|284|301+310|302+350|302+352|304+340|305+351+338|310|320|321|330|332+313|361|362|363|390|391|403+233|404|405|501}}
| LD50 = 123 mg/kg (oral, rat)
| NFPA-H = 4
| NFPA-F = 1
| NFPA-R = 1
| NFPA-S = 
| FlashPtC = 320
  }}<!--
| [Specific Heat Capacity](/source/Specific_Heat_Capacity) = 0.498185 J/g-°C<BR/> [Heat of Formation](/source/Heat_of_Formation) = 146 kJ/mol
 -->
| Section8       = {{Chembox Related
| OtherAnions = [AgCl](/source/Silver_chloride)
| OtherCations = [NaCN](/source/Sodium_cyanide)<br /> [Copper(I) cyanide](/source/Copper(I)_cyanide)
  }}
}}
'''Silver cyanide''' is the [chemical compound](/source/chemical_compound) with the [formula](/source/chemical_formula) AgCN. It is a white salt that is [precipitated](/source/Precipitation_(chemistry)) upon treatment of solutions containing Ag<sup>+</sup> with [cyanide](/source/cyanide), which is used in some schemes to recover silver from solution. Silver cyanide is used in silver-plating.

==Structure==
The structure of silver cyanide consists of -[Ag-CN]- chains in which the linear two-coordinate Ag<sup>+</sup> ions are bridged by the cyanide ions,<ref>{{ cite journal | title = Crystal Structures of AuCN and AgCN and Vibrational Spectroscopic Studies of AuCN, AgCN, and CuCN | first1 = Graham A. | last1 = Bowmaker | first2 = Brendan J. | last2 = Kennedy | first3 = Jason C. | last3 = Reid | journal = [Inorg. Chem.](/source/Inorganic_Chemistry_(journal)) | year = 1998 | volume = 37 | issue = 16 | pages = 3968–3974  | doi = 10.1021/ic9714697 | pmid = 11670511 }}</ref> typical of silver(I) and other d<sup>10</sup> ions. This is the same binding mode as seen in the more famous case of [Prussian blue](/source/Prussian_blue). These chains then pack hexagonally with adjacent chains offset by +/- 1/3 of the ''c'' lattice parameter. This is the same as the structure adopted by the high temperature polymorph of [copper(I) cyanide](/source/copper(I)_cyanide). The silver to carbon and silver to nitrogen bond lengths in AgCN are both ~2.06 Å<ref>{{ cite journal | last1 = Hibble | first1 = S. J. | last2 = Cheyne | first2 = S. M. | last3 = Hannon | first3 = A. C. | last4 = Eversfield | first4 = S. G. | title = Beyond Bragg scattering: the structure of AgCN determined from total neutron diffraction | journal = Inorganic Chemistry | year = 2002 | volume = 41 | issue = 5 | pages = 1042–1044 | doi = 10.1021/ic015610u | pmid = 11874335 }}</ref> and the cyanide groups show head-to-tail disorder.<ref>{{Cite journal|last1=Bryce|first1=David L.|last2=Wasylishen|first2=Roderick E.|date=2002|title=Insight into the Structure of Silver Cyanide from <sup>13</sup>C and <sup>15</sup>N Solid-State NMR Spectroscopy|journal=Inorganic Chemistry|language=en|volume=41|issue=16|pages=4131–4138|doi=10.1021/ic0201553|pmid=12160400|issn=0020-1669}}</ref>

==Uses==
"Cyanidation" is widely used in the isolation of silver from its ores.  Partial purification of silver compounds is usually effected by [froth flotation](/source/froth_flotation).  The silver ion is then separated from the skimmed froth with cyanide, yielding a solution of [Ag(CN)<sub>2</sub>]<sup>−</sup>.  The silver metal can then be plated out by electrolysis of such solutions.<ref name=KO>{{cite book |doi=10.1002/0471238961.1909122205201809.a01.pub3|chapter=Silver and Silver Alloys |title=Kirk-Othmer Encyclopedia of Chemical Technology |year=2010 |last1=Etris |first1=S. F. |pages=1–43 |isbn=978-0471238966 }}</ref>

Both AgCN and [KAg(CN)<sub>2</sub>](/source/Potassium_argentocyanide) have been used in silver-plating solutions since at least 1840 when the Elkington brothers patented their recipe for a silver-plating solution. A typical, traditional silver-plating solution would contain 15-40 g·L<sup>−1</sup> KAg(CN)<sub>2</sub> , 12-120 g·L<sup>−1</sup> KCN and 15 g·L<sup>−1</sup> K<sub>2</sub>CO<sub>3</sub>.<ref>{{Cite journal|last=Blair|first=Alan|date=2000|title=Silver plating|journal=Metal Finishing|language=en|volume=98|issue=1|pages=298–303|doi=10.1016/S0026-0576(00)80339-6}}</ref>

==Reactions==
AgCN precipitates upon the addition of [sodium cyanide](/source/sodium_cyanide) to a solution containing Ag<sup>+</sup>.  On the addition of further cyanide, the precipitate dissolves to form linear [Ag(CN)<sub>2</sub>]<sup>−</sup><sub>(aq)</sub> and [Ag(CN)<sub>3</sub>]<sup>2−</sup><sub>(aq)</sub>. Silver cyanide is also soluble in solutions containing other ligands such as ammonia or tertiary [phosphine](/source/phosphine)s.

Silver cyanides form structurally complex materials upon reaction with other anions.<ref>{{Cite journal|last1=Urban|first1=Victoria|last2=Pretsch|first2=Thorsten|last3=Hartl|first3=Hans|date=2005-04-29|title=From AgCN Chains to a Fivefold Helix and a Fishnet-Shaped Framework Structure|journal=Angewandte Chemie International Edition|language=en|volume=44|issue=18|pages=2794–2797|doi=10.1002/anie.200462793|pmid=15830404|issn=1433-7851}}</ref>  Some silver cyanides are [luminescent](/source/luminescent).<ref>{{Cite journal|last1=Omary|first1=Mohammad A.|last2=Webb|first2=Thomas R.|last3=Assefa|first3=Zerihun|last4=Shankle|first4=George E.|last5=Patterson|first5=Howard H.|date=1998|title=Crystal Structure, Electronic Structure, and Temperature-Dependent Raman Spectra of Tl[Ag(CN)<sub>2</sub>]: Evidence for Ligand-Unsupported Argentophilic Interactions|journal=Inorganic Chemistry|language=en|volume=37|issue=6|pages=1380–1386|doi=10.1021/ic970694l|pmid=11670349|issn=0020-1669}}</ref>

==See also==
* [List of compounds with carbon number 1](/source/List_of_compounds_with_carbon_number_1)

==References==
{{reflist}}

{{Cyanides}}
{{Silver compounds}}

Category:Cyanides
Category:Silver compounds

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Adapted from the Wikipedia article [Silver cyanide](https://en.wikipedia.org/wiki/Silver_cyanide) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Silver_cyanide?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.