{{Chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 400833775 | ImageFile = Manganous chloride anh.jpg | ImageCaption = Anhydrous | ImageFile1 = Manganese(II)_chloride_tetrahydrate.jpg | ImageCaption1 = Tetrahydrate | IUPACName = Manganese(II) chloride<br/>Manganese dichloride | OtherNames = Manganous chloride<br /> hyperchloride of manganese |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 22888 | ChEMBL_Ref = {{ebicite|changed|EBI}} | ChEMBL = 1200693 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 6YB4901Y90 | UNII1_Ref = {{fdacite|correct|FDA}} | UNII1 = QQE170PANO | UNII1_Comment = (tetrahydrate) | InChIKey = GLFNIEUTAYBVOC-NUQVWONBAP | InChI = 1S/2ClH.Mn/h2*1H;/q;;+2/p-2 | SMILES = [Mn+2].[Cl-].[Cl-] | SMILES_Comment = anhydrous | SMILES1 = Cl[Mn-4]([OH2+])(Cl)([OH2+])([OH2+])[OH2+] | SMILES1_Comment = tetrahydrate | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/2ClH.Mn/h2*1H;/q;;+2/p-2 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = GLFNIEUTAYBVOC-UHFFFAOYSA-L | InChIKey1 = GLFNIEUTAYBVOC-UHFFFAOYSA-L | CASNo = 7773-01-5 | CASNo_Ref = {{cascite|correct|CAS}} | CASNo1_Ref = {{cascite|changed|??}} | CASNo1 = 20603-88-7 | CASNo1_Comment = (dihydrate) | CASNo2_Ref = {{cascite|correct|CAS}} | CASNo2 = 13446-34-9 | CASNo2_Comment = (tetrahydrate) | EINECS = | PubChem = 24480 | RTECS = OO9625000 }} |Section2={{Chembox Properties | Formula = MnCl<sub>2</sub> | MolarMass = 125.844 g/mol (anhydrous)<br/>161.874 g/mol (dihydrate)<br/>197.91 g/mol (tetrahydrate) | Appearance = pink solid (tetrahydrate) | Density = 2.977 g/cm<sup>3</sup> (anhydrous) <br> 2.27 g/cm<sup>3</sup> (dihydrate) <br> 2.01 g/cm<sup>3</sup> (tetrahydrate) | MeltingPtC = 654 | MeltingPt_notes = (anhydrous) <br> dihydrate dehydrates at 135 °C <br> tetrahydrate dehydrates at 58 °C | BoilingPtC = 1225 | BoilingPt_notes = | Solubility = 63.4 g/100 ml (0 °C) <br> 73.9 g/100 ml (20 °C) <br> 88.5 g/100 ml (40 °C) <br> 123.8 g/100 ml (100 °C) | SolubleOther = slightly soluble in pyridine, soluble in ethanol <br> insoluble in ether | Solvent = | pKa = | pKb = | MagSus = +14,350·10<sup>−6</sup> cm<sup>3</sup>/mol }} |Section3={{Chembox Structure | CrystalStruct = CdCl<sub>2</sub> | Coordination = octahedral | MolShape = }} |Section7={{Chembox Hazards | ExternalSDS = | MainHazards = | NFPA-H = 2 | NFPA-F = 0 | NFPA-R = 0 | NFPA-S = | FlashPt = Non-flammable | PEL = | LD50 = 250-275 mg/kg (rat, oral){{citation needed|date=July 2015}}<br/>1715 mg/kg (mouse, oral)<ref>{{IDLH|7439965|Manganese compounds (as Mn)}}</ref> }} |Section8={{Chembox Related | OtherAnions = Manganese(II) fluoride<br/>Manganese(II) bromide<br/>Manganese(II) iodide | OtherCations = Manganese(III) chloride<br/>Technetium(IV) chloride<br/>Rhenium(III) chloride<br/>Rhenium(IV) chloride<br/>Rhenium(V) chloride<br/>Rhenium(VI) chloride | OtherFunction = | OtherFunction_label = | OtherCompounds = Chromium(II) chloride<br/>Iron(II) chloride }} }}
'''Manganese(II) chloride''' is the dichloride salt of manganese, MnCl<sub>2</sub>. This inorganic chemical exists in the anhydrous form, as well as the dihydrate (MnCl<sub>2</sub>·2H<sub>2</sub>O) and tetrahydrate (MnCl<sub>2</sub>·4H<sub>2</sub>O), with the tetrahydrate being the most common form. Like many Mn(II) species, these salts are pink, with the paleness of the color being characteristic of transition metal complexes with high spin d<sup>5</sup> configurations.<ref>N. N. Greenwood, A. Earnshaw, ''Chemistry of the Elements'', 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.</ref>
==Preparation== Manganese chloride is produced by treating manganese(IV) oxide with concentrated hydrochloric acid. :MnO<sub>2</sub> + 4 HCl → MnCl<sub>2</sub> + 2 H<sub>2</sub>O + Cl<sub>2</sub> In the 19th century this reaction was used for the manufacture of chlorine. By carefully neutralizing the resulting solution with MnCO<sub>3</sub>, one can selectively precipitate iron salts, which are common impurities in manganese dioxide.<ref name=Ullmann>{{citation | first = Arno H. | last = Reidies | contribution = Manganese Compounds | title = Ullmann's Encyclopedia of Industrial Chemistry | publisher = Wiley-VCH | location = Weinheim | year = 2002 | doi = 10.1002/14356007.a16_123 | isbn = 978-3-527-30385-4}}.</ref> In the laboratory, manganese chloride can be prepared by treating manganese metal or manganese(II) carbonate with hydrochloric acid: :Mn + 2 HCl + 4 H<sub>2</sub>O → MnCl<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub> + H<sub>2</sub> :MnCO<sub>3</sub> + 2 HCl + 3 H<sub>2</sub>O → MnCl<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub> + CO<sub>2</sub>
===Structures=== Anhydrous MnCl<sub>2</sub> adopts a layered cadmium chloride-like structure. The tetrahydrate consists of octahedral ''cis''-Mn(H<sub>2</sub>O)<sub>4</sub>Cl<sub>2</sub> molecules. The trans isomer, which is metastable, is also known.<ref>{{cite journal|title=Crystal structure of manganese dichloride tetrahydrate|author1=Zalkin, Allan|author2=Forrester, J. D.|author3=Templeton, David H.|journal=Inorganic Chemistry|year=1964|volume=3|issue=4|pages=529–33|doi=10.1021/ic50014a017|url=http://www.escholarship.org/uc/item/7vf7p79j}}</ref><ref>A. F. Wells, ''Structural Inorganic Chemistry'', 5th ed., Oxford University Press, Oxford, UK, 1984.</ref> The dihydrate MnCl<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub> is a coordination polymer. Each Mn center is coordinated to four doubly bridging chloride ligands. The octahedron is completed by a pair of mutually trans aquo ligands.<ref>{{cite journal|title=Crystal structures of manganese(II) and iron(II) chloride dihydrate|author1=Morosin, B.|author2=Graeber, E. J.|journal=Journal of Chemical Physics|year=1965|volume=42|issue=3|pages=898–901|doi=10.1063/1.1696078|bibcode=1965JChPh..42..898M}}</ref> {{multiple image | align = center | width = 200 | footer = Structures of the forms of manganese(II) chloride | image1 = manganese(II)-chloride-xtal-layer-top-infinite-3D-bs-17.png | alt1 = | caption1 = Anhydrous | image2 = MX2(H2O)2.png | alt2 = | caption2 = Dihydrate}}
==Chemical properties== The hydrates dissolve in water to give mildly acidic solutions with a pH of around 4. These solutions consist of the metal aquo complex [Mn(H<sub>2</sub>O)<sub>6</sub>]<sup>2+</sup>.
It is a weak Lewis acid, reacting with chloride ions to produce a series of salts containing the following ions [MnCl<sub>3</sub>]<sup><nowiki>−</nowiki></sup>, [MnCl<sub>4</sub>]<sup>2<nowiki>−</nowiki></sup>, and [MnCl<sub>6</sub>]<sup>4<nowiki>−</nowiki></sup>.
Upon treatment with typical organic ligands, manganese(II) undergoes oxidation by air to give Mn(III) complexes. Examples include [Mn(EDTA)]<sup><nowiki>−</nowiki></sup>, [Mn(CN)<sub>6</sub>]<sup>3<nowiki>−</nowiki></sup>, and [Mn(acetylacetonate)<sub>3</sub>]. Triphenylphosphine forms a labile 2:1 adduct: :MnCl<sub>2</sub> + 2 Ph<sub>3</sub>P → [MnCl<sub>2</sub>(Ph<sub>3</sub>P)<sub>2</sub>]
Anhydrous manganese(II) chloride serves as a starting point for the synthesis of a variety of organomanganese compounds. For example, manganocene is prepared by reaction of MnCl<sub>2</sub> with a solution of sodium cyclopentadienide in tetrahydrofuran (THF). :MnCl<sub>2</sub> + 2 NaC<sub>5</sub>H<sub>5</sub> → Mn(C<sub>5</sub>H<sub>5</sub>)<sub>2</sub> + 2 NaCl Similar reactions are used in the preparation of the antiknock compound methylcyclopentadienyl manganese tricarbonyl.<ref name=Ullmann/>
Manganese chloride is a precursor to organomanganese reagents in organic chemistry.<ref>{{cite journal |doi=10.15227/orgsyn.076.0239|title=Regioselective Monoalkylation of Ketones Via Their Manganese Enolates: 2-Benzyl-6-Methylcyclohexanone from 2-Methylcyclohexanone |journal=Organic Syntheses |year=1999 |volume=76 |page=239|author=Gérard Cahiez, François Chau, Bernard Blanchot }}</ref><ref>{{cite journal |doi=10.15227/orgsyn.072.0135|title=Manganese-Copper-Catalyzed Conjugate Addition of Organomagnesium Reagents to a,b-Ethylenic Ketones\: 2-(1,1-Dimethylpentyl)-5-methyl-cyclohexanone from Pulegone |journal=Organic Syntheses |year=1995 |volume=72 |page=135|author=S. Marquais, M. Alami, and G. Cahiez }}</ref>
Manganese chloride is mainly used in the production of dry cell batteries.
===Magnetism=== Manganese(II) salts are paramagnetic. As such the presence of such salts profoundly affect NMR spectra.<ref> {{Citation | last1 = Frohlich | first1 = Margret | last2 = Brecht | first2 = Volker | last3 = Peschka-Suss | first3 = Regine | title = Parameters influencing the determination of liposome lamellarity by <sup>31P</sup>-NMR | journal = Chemistry and Physics of Lipids | volume = 109 | issue = 1 | pages = 103–112 | date = January 2001 | doi = 10.1016/S0009-3084(00)00220-6 | pmid = 11163348 }} </ref>
==Natural occurrence== Scacchite is the natural, anhydrous form of manganese(II) chloride.<ref>{{Cite web|url=https://www.mindat.org/min-3549.html|title=Scacchite}}</ref>
==Precautions== Manganism, or manganese poisoning, can be caused by long-term exposure to manganese dust or fumes.
==References== {{reflist}}
==External links== {{Commons category|Manganese(II) chloride}} *[http://www.npi.gov.au/resource/manganese-compounds National Pollutant Inventory: Manganese and compounds Fact Sheet]
{{Manganese compounds}} {{Chlorides}}
Category:Chlorides Category:Manganese(II) compounds Category:Metal halides