| Revision as of 12:46, 15 February 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 473094302 of page Chromium(II)_chloride for the Chem/Drugbox validation project (updated: ''). |
Latest revision as of 16:46, 12 July 2024 edit AnDeargMor (talk | contribs)Extended confirmed users797 edits Changed model to ionic to reflect on high melting and boiling points, added tetrahydrate |
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{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}} |
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{{chembox |
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{{chembox |
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| Watchedfields = changed |
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| verifiedrevid = 419088226 |
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| verifiedrevid = 476996240 |
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| Name = Chromium(II) chloride |
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| Name = Chromium(II) chloride |
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| ImageFile = Hydrophilite.GIF |
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| ImageFile = Rutile-unit-cell-3D-balls.png |
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| ImageName = 3D model of chromium(II) chloride, green atom is chloride |
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| ImageFile1 = Chromium(II) chloride.JPG |
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| ImageSize1 = 160px |
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| ImageName1 = Sample of chromium(II) chloride |
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| IUPACName = Chromium(II) chloride |
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| IUPACName = Chromium(II) chloride |
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| OtherNames = Chromous chloride |
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| OtherNames = Chromous chloride |
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| Section1 = {{Chembox Identifiers |
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|Section1={{Chembox Identifiers |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 23252 |
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| ChemSpiderID = 23252 |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| UNII = CET32HKA21 |
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| UNII = CET32HKA21 |
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| UNII_Comment = (anhydrous) |
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| UNII1_Ref = {{fdacite|correct|FDA}} |
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| UNII1 = Q781GP5E2W |
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| UNII1_Comment = (tetrahydrate) |
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| EC_number = 233-163-3 |
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| UNNumber = 3077 |
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| InChI = 1/2ClH.Cr/h2*1H;/q;;+2/p-2 |
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| InChI = 1/2ClH.Cr/h2*1H;/q;;+2/p-2 |
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| SMILES = ClCl |
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| SMILES = .. |
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| SMILES_Comment = anhydrous |
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| SMILES1 = Cl(Cl)()()() |
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| SMILES1_Comment = tetrahydrate |
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| InChIKey = XBWRJSSJWDOUSJ-NUQVWONBAQ |
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| InChIKey = XBWRJSSJWDOUSJ-NUQVWONBAQ |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = XBWRJSSJWDOUSJ-UHFFFAOYSA-L |
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| StdInChIKey = XBWRJSSJWDOUSJ-UHFFFAOYSA-L |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo = 10049-05-5 |
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| CASNo = 10049-05-5 |
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| CASNo_Comment = (anhydrous) |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo1_Ref = {{cascite|correct|CAS}} |
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| CASNo1 = 13931-94-7 |
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| CASNo1_Comment =(tetrahydrate) |
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| PubChem = 24871 |
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| PubChem = 24871 |
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| RTECS = GB5250000 |
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| RTECS = GB5250000 |
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}} |
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}} |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Cr=1 | Cl=2 |
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| Formula = CrCl<sub>2</sub> |
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| Appearance = White to grey/green powder (anhydrous)<br>blue solid (tetrahydrate) |
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| MolarMass = 122.9021 g/mol |
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| ExactMass = 121.878217 |
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| Odor = Odorless |
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| Density = 2.88 g/cm<sup>3</sup> (24 °C)<ref name=crc /> |
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| Appearance = white crystalline solid <br> very ] |
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| Odor = odorless |
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| MeltingPtC = 824 |
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| MeltingPt_notes = <br> anhydrous<br> {{convert|51|C|F K}}<br> tetrahydrate, decomposes<ref name=crc /> |
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| Density = 2.9 g/cm<sup>3</sup> |
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| MeltingPt = 824 °C |
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| BoilingPtC = 1302 |
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| BoilingPt_notes = <br> anhydrous<ref name=crc>{{CRC90}}</ref> |
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| BoilingPt = 1120 °C |
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| Solubility = very soluble |
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| Solubility = Soluble<ref name=crc /> |
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| SolubleOther = insoluble in ], ] |
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| SolubleOther = Insoluble in ], ] |
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| pKa = 2+ |
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| pKa = 2 |
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| MagSus = +7230·10<sup>−6</sup> cm<sup>3</sup>/mol |
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}} |
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}} |
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| Section3 = {{Chembox Structure |
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|Section3={{Chembox Structure |
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| Coordination = ], 6-coordinate |
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| Coordination = ] (Cr<sup>2+</sup>, anhydrous)<ref name=iucr /> |
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| CrystalStruct = ] (deformed ]), ] |
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| CrystalStruct = ] (deformed ], anhydrous), ]<ref name=iucr>{{cite journal|doi = 10.1107/S0365110X61002710|last1 = Tracy|first1 = Joseph W.|last2 = Gregory|first2 = N.W.|last3 = Lingafelter|first3 = E.C.|last4 = Dunitz|first4 = J.D.|last5 = Mez|first5 = H.-C.|last6 = Rundle|first6 = R.E.|last7 = Scheringer|first7 = Christian|last8 = Yakel|first8 = H.L.|last9 = Wilkinson|first9 = M.K.|journal = Acta Crystallographica|volume = 4|pages = 927–929|year = 1961|issue = 9|title = The crystal structure of chromium(II) chloride|doi-access = free}}</ref><br> ] (tetrahydrate)<ref name=zeit /> |
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| SpaceGroup = Pnnm, No. 58 |
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| SpaceGroup = Pnnm, No. 58 (anhydrous)<ref name=iucr /><br> P2<sub>1</sub>/c, No. 14 (tetrahydrate)<ref name=zeit /> |
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}} |
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| PointGroup = 2/m 2/m 2/m (anhydrous)<ref name=iucr /><br> 2/m (tetrahydrate)<ref name=zeit /> |
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| Section7 = {{Chembox Hazards |
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| LattConst_a = 6.64 Å |
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| ExternalMSDS = |
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| LattConst_b = 5.98 Å |
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| EUIndex = Not listed |
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| LattConst_c = 3.48 Å (anhydrous)<ref name=iucr /> |
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| LD50 = 1870 mg/kg (oral, rat) |
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| LattConst_alpha = 90 |
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}} |
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}} |
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| Section8 = {{Chembox Other |
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|Section4={{Chembox Thermochemistry |
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| OtherAnions = ]<br/>]<br/>] |
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| DeltaHf = −395.4 kJ/mol<ref name=crc /> |
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| OtherCations = ]<br/>]<br/>]<br/>] |
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| Entropy = 115.3 J/mol·K<ref name=crc /> |
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}} |
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| HeatCapacity = 71.2 J/mol·K<ref name=crc /> |
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| DeltaGf = −356 kJ/mol<ref name=crc /> |
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}} |
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|Section7={{Chembox Hazards |
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| ExternalSDS = |
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| GHSPictograms = {{GHS07}}<ref name="sigma">{{Sigma-Aldrich|id=450782|name=Chromium(II) chloride|accessdate=2014-07-04}}</ref> |
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| GHSSignalWord = Warning |
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| HPhrases = {{H-phrases|302|315|319|335}}<ref name="sigma" /> |
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| PPhrases = {{P-phrases|261|305+351+338}}<ref name="sigma" /> |
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| NFPA-H = 2 |
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| NFPA-F = 0 |
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| NFPA-R = 1 |
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| NFPA_ref = <ref name=fca>{{cite web|url = https://www.fishersci.ca/viewmsds.do?catNo=AC315190250|title = MSDS of Chromium(II) chloride|website = fishersci.ca|access-date = 2014-07-04|publisher = Fisher Scientific}}</ref> |
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| LD50 = 1870 mg/kg (rats, oral)<ref name=fca /> |
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}} |
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|Section8={{Chembox Related |
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| OtherAnions = ]<br> ]<br> ] |
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| OtherCations = ]<br> ]<br> ]<br> ] |
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}} |
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}} |
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}} |
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'''Chromium(II) chloride''' describes ]s with the ] ]]<sub>2</sub>(H<sub>2</sub>O)<sub>n</sub>. The anhydrous solid is white when pure, however commercial samples are often grey or green; it is ] and readily dissolves in water to give bright blue air-sensitive solutions of the tetrahydrate Cr(H<sub>2</sub>O)<sub>4</sub>Cl<sub>2</sub>. Chromium(II) chloride has no commercial uses but is used on a laboratory-scale for the synthesis of other chromium complexes. |
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==Synthesis== |
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CrCl<sub>2</sub> is produced by reducing ] either with ] at 500 °C: |
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:2{{nbsp}}CrCl<sub>3</sub> + H<sub>2</sub> → 2{{nbsp}}CrCl<sub>2</sub> + 2{{nbsp}}HCl |
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or by electrolysis. |
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On the laboratory scale, ], ], and related reductants produce chromous chloride from chromium(III) precursors: |
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:4 CrCl<sub>3</sub> + LiAlH<sub>4</sub> → 4 CrCl<sub>2</sub> + LiCl + AlCl<sub>3</sub> + 2 H<sub>2</sub> |
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:2 CrCl<sub>3</sub> + Zn → 2 CrCl<sub>2</sub> + ZnCl<sub>2</sub> |
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CrCl<sub>2</sub> can also be prepared by treating a solution of ] with ]:<ref name=brauer>{{cite book|last=Riley|first=edited by Georg Brauer ; translated by Scripta Technica, Inc. Translation editor Reed F.|title=Handbook of Preparative Inorganic Chemistry. Volume 1|date=1963|publisher=Academic Press|location=New York, N.Y.|isbn=978-0121266011|page=1337|edition=2nd}}</ref> |
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:Cr<sub>2</sub>(OAc)<sub>4</sub> + 4 HCl → 2 CrCl<sub>2</sub> + 4 AcOH |
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Treatment of chromium powder with concentrated ] gives a blue hydrated chromium(II) chloride, which can be converted to a related ].<ref>{{cite book |doi=10.1002/9780470132418.ch4|chapter=Chromium(II) Salts and Complexes|series=Inorganic Syntheses|year=1967|volume=10|last1=Holah|first1=David G.|author2-link=John P. Fackler Jr.|last2=Fackler|first2=John P.|title=Inorganic Syntheses |pages=26–35|isbn=9780470132418 }}</ref> |
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:Cr + n{{nbsp}}H<sub>2</sub>O + 2{{nbsp}}HCl → CrCl<sub>2</sub>(H<sub>2</sub>O)<sub>n</sub> + H<sub>2</sub> |
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==Structure and properties== |
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Anhydrous CrCl<sub>2</sub> is white<ref name=brauer/> however commercial samples are often grey or green. It crystallizes in the ''Pnnm'' ], which is an orthorhombically distorted variant of the ] structure; making it isostructural to ]. The Cr centres are ], being distorted by the ].<ref>{{Greenwood&Earnshaw2nd|pages=1021–1022}}</ref> |
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] |
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The hydrated derivative, CrCl<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>, forms ] crystals with the ''P2<sub>1</sub>/c'' space group. The molecular geometry is approximately octahedral consisting of four short Cr—O bonds (2.078 Å) arranged in a square planar configuration and two longer Cr—Cl bonds (2.758 Å) in a trans configuration.<ref name=zeit>{{cite journal|first1 = H.G. von|last1 = Schnering|first2 = B.-H.|last2 = Brand|doi = 10.1002/zaac.19734020206|title = Struktur und Eigenschaften des blauen Chrom(II)-chlorid-tetrahydrats CrCl<sub>2</sub>.4H<sub>2</sub>O|year = 1973|volume = 402|issue = 2|pages = 159–168|journal = Zeitschrift für anorganische und allgemeine Chemie}}</ref> |
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==Reactions== |
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The ] for Cr<sup>3+</sup> + e<sup>−</sup> ⇄ Cr<sup>2+</sup> is −0.41. Since the reduction potential of H<sup>+</sup> to H<sub>2</sub> in acidic conditions is +0.00, the chromous ion has sufficient potential to reduce acids to hydrogen, although this reaction does not occur without a catalyst. |
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===Organic chemistry=== |
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Chromium(II) chloride is used as precursor to other inorganic and organometallic chromium complexes. Alkyl halides and nitroaromatics are reduced by CrCl<sub>2</sub>. The moderate electronegativity of chromium and the range of substrates that CrCl<sub>2</sub> can accommodate make ] very synthetically versatile.<ref>(a) Kazuhiko Takai, K.; Loh, T.-P. "Chromium(II) Chloride" in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons: New York; 2005. {{doi|10.1002/047084289X.rc166}}. (b) Alois Fürstner, "Carbon−Carbon Bond Formations Involving Organochromium(III) Reagents" Chemical Reviews, 1999, 99 (4), 991–1046 {{doi|10.1021/cr9703360}}</ref> It is a reagent in the ], a useful method for preparing medium-size rings.<ref>(a) MacMillan, D. W. C.; Overman, Larry E. "Enantioselective Total Synthesis of (−)-7-Deacetoxyalcyonin Acetate. First Synthesis of a Eunicellin Diterpene" J. Am. Chem. Soc. 1995, 117 (41), 10391–10392. {{doi|10.1021/ja00146a028}}. (b) Lotesta, S. D.; Liu, J.; Yates, E. V.; Krieger, I.; Sacchettini, J. C.; Freundlich, J. S.; Sorensen, E. J. "Expanding the pleuromutilin class of antibiotics by de novo chemical synthesis" Chem. Sci. 2011, 2, 1258-1261. {{doi|10.1039/C1SC00116G}}.</ref> It is also used in the ] to form vinyl iodides from aldehydes in the presence of ].<ref>Simple and selective method for aldehydes (RCHO) -> (E)-haloalkenes (RCH:CHX) conversion by means of a haloform-chromous chloride system K. Takai, K. Nitta, K. Utimoto J. Am. Chem. Soc.; 1986; 108(23); 7408-7410. {{doi|10.1021/ja00283a046}}.</ref> |
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==References== |
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{{reflist}} |
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{{Chromium compounds}} |
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{{Chlorides}} |
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] |
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] |
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] |
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] |