Manganese(II) chloride

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Manganese(II) chloride
Anhydrous
Tetrahydrate
Names
IUPAC names
Manganese(II) chloride
Manganese dichloride
Other names
Manganous chloride
hyperchloride of manganese
Identifiers
3D model (
JSmol
)
ChEMBL
ChemSpider
ECHA InfoCard
 100.028.972 Edit this at Wikidata
RTECS number
  • OO9625000
UNII
  • InChI=1S/2ClH.Mn/h2*1H;/q;;+2/p-2 checkY
    Key: GLFNIEUTAYBVOC-UHFFFAOYSA-L checkY
  • InChI=1S/2ClH.Mn/h2*1H;/q;;+2/p-2
    Key: GLFNIEUTAYBVOC-NUQVWONBAP
  • Key: GLFNIEUTAYBVOC-UHFFFAOYSA-L
SMILES
  • anhydrous: [Mn+2].[Cl-].[Cl-]
  • tetrahydrate: Cl[Mn-4]([OH2+])(Cl)([OH2+])([OH2+])[OH2+]
Properties
MnCl2
Molar mass 125.844 g/mol (anhydrous)
161.874 g/mol (dihydrate)
197.91 g/mol (tetrahydrate)
Appearance pink solid (tetrahydrate)
Density 2.977 g/cm3 (anhydrous)
2.27 g/cm3 (dihydrate)
2.01 g/cm3 (tetrahydrate)
Melting point 654 °C (1,209 °F; 927 K) (anhydrous)
dihydrate dehydrates at 135 °C
tetrahydrate dehydrates at 58 °C
Boiling point 1,225 °C (2,237 °F; 1,498 K)
63.4 g/100 ml (0 °C)
73.9 g/100 ml (20 °C)
88.5 g/100 ml (40 °C)
123.8 g/100 ml (100 °C)
Solubility slightly soluble in pyridine, soluble in ethanol
insoluble in ether
+14,350·10−6 cm3/mol
Structure
CdCl2
octahedral
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
250-275 mg/kg (rat, oral)[citation needed]
1715 mg/kg (mouse, oral)[1]
Related compounds
Other anions
 Manganese(II) fluoride
Manganese(II) bromide
Manganese(II) iodide
Other cations
Rhenium(V) chloride
Rhenium(VI) chloride
Related compounds
 Chromium(II) chloride
Iron(II) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Manganese(II) chloride is the di

high spin d5 configurations.[2]

Preparation

Manganese chloride is produced by treating

manganese(IV) oxide
with concentrated hydrochloric acid.

MnO2 + 4 HCl → MnCl2 + 2 H2O + Cl2

In the 19th century this reaction was used for the manufacture of chlorine. By carefully neutralizing the resulting solution with MnCO3, one can selectively precipitate iron salts, which are common impurities in manganese dioxide.[3] In the laboratory, manganese chloride can be prepared by treating manganese metal or manganese(II) carbonate with hydrochloric acid:

Mn + 2 HCl + 4 H2O → MnCl2(H2O)4 + H2
MnCO3 + 2 HCl + 3 H2O → MnCl2(H2O)4 + CO2

Structures

Anhydrous MnCl2 adopts a layered

aquo ligands.[6]

Anhydrous
Dihydrate
Structures of the forms of manganese(II) chloride

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(H2O)6]2+.

It is a weak

Lewis acid, reacting with chloride
ions to produce a series of salts containing the following ions [MnCl3]−, [MnCl4]2−, and [MnCl6]4−.

Upon treatment with typical organic ligands, manganese(II) undergoes oxidation by air to give Mn(III)

acetylacetonate)3]. Triphenylphosphine forms a labile 2:1 adduct
:

MnCl2 + 2 Ph3P → [MnCl2(Ph3P)2]

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 MnCl2 with a solution of sodium cyclopentadienide in tetrahydrofuran
(THF).

MnCl2 + 2 NaC5H5 → Mn(C5H5)2 + 2 NaCl

Similar reactions are used in the preparation of the antiknock compound methylcyclopentadienyl manganese tricarbonyl.[3]

Manganese chloride is a precursor to organomanganese reagents in organic chemistry.[7][8]

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.[9]

Natural occurrence

Scacchite is the natural, anhydrous form of manganese(II) chloride.[10]

Precautions

Manganism, or manganese poisoning, can be caused by long-term exposure to manganese dust or fumes.

References

  1. ^ "Manganese compounds (as Mn)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  2. ^ N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
  3. ^
    ISBN 978-3-527-30385-4
    .
  4. doi:10.1021/ic50014a017
    .
  5. ^ A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
  6. doi:10.1063/1.1696078
    .
  7. doi:10.15227/orgsyn.076.0239.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  8. doi:10.15227/orgsyn.072.0135.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  9. ^ Frohlich, Margret; Brecht, Volker; Peschka-Suss, Regine (January 2001), "Parameters influencing the determination of liposome lamellarity by 31P-NMR", Chemistry and Physics of Lipids, 109 (1): 103–112,
    PMID 11163348
  10. ^ "Scacchite".
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