Silver cyanide

{{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. | 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/cm³ | Solubility = 0.000023 g/100 mL (20 °C) | SolubleOther = soluble in concentrated ammonia, boiling nitric acid, ammonium hydroxide, KCN <br> insoluble in alcohol, dilute 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;43.2·10⁻⁶ cm³/mol }} | Section3 = {{Chembox Structure | Coordination = linear | CrystalStruct = hexagonal }} | Section4 = {{Chembox Thermochemistry | DeltaHf = 146&nbsp;kJ·mol⁻¹<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⁻¹·K⁻¹<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 = 0.498185 J/g-°C<BR/> Heat of Formation = 146 kJ/mol --> | Section8 = {{Chembox Related | OtherAnions = AgCl | OtherCations = NaCN<br /> Copper(I) cyanide }} }} '''Silver cyanide''' is the chemical compound with the formula AgCN. It is a white salt that is precipitated upon treatment of solutions containing Ag⁺ with 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⁺ 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. | year = 1998 | volume = 37 | issue = 16 | pages = 3968–3974 | doi = 10.1021/ic9714697 | pmid = 11670511 }}</ref> typical of silver(I) and other d¹⁰ ions. This is the same binding mode as seen in the more famous case of 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. 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 ¹³C and ¹⁵N 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. The silver ion is then separated from the skimmed froth with cyanide, yielding a solution of [Ag(CN)₂]⁻. 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)₂ 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⁻¹ KAg(CN)₂ , 12-120 g·L⁻¹ KCN and 15 g·L⁻¹ K₂CO₃.<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 to a solution containing Ag⁺. On the addition of further cyanide, the precipitate dissolves to form linear [Ag(CN)₂]⁻_(aq) and [Ag(CN)₃]²⁻_(aq). Silver cyanide is also soluble in solutions containing other ligands such as ammonia or tertiary phosphines.

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.<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)₂]: 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

==References== {{reflist}}

{{Cyanides}} {{Silver compounds}}

Category:Cyanides Category:Silver compounds