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Manganese(II) chloride

Manganese(II) chloride
Other names Manganous chloride
Molecular formula MnCl2
Molar mass anhydrous 125.844 g/mol

dihydrate 161.874 g/mol

tetrahydrate 197.91 g·mol−1

Appearance pink solid
CAS number 7773-01-5
Density and phase 3.0 g/cm³, solid
Solubility in water 72.3 g/100 ml (25 °C)
Melting point 654 °C
Boiling point 1225 °C
Crystal structure CdCl2
MSDS External MSDS
EU classification  
Flash point non-flammable
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions Manganese(II) fluoride
Manganese(II) bromide
Manganese(II) iodide
Other cations Manganese(III) chloride
Technetium(IV) chloride
Rhenium(IV) chloride
Related compounds Chromium(II) chloride
Iron(II) chloride
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

Manganese(II) chloride describes a series of compounds with the formula MnCl2(H2O)x, where the value of x can be 0, 2, or 4. The tetrahydrate is a pink salt that occurs naturally as the rare mineral scacchite. Most commonly, the term "manganese(II) chloride" refers to the tetrahydrate MnCl2·4H2O, which consists of octahedral trans-Mn(H2O)4Cl2 molecules. The dihydrate MnCl2·2H2O is also known. Many Mn(II) species are characteristically pink, the paleness of the color being characteristic of transition metal complexes with high spin d5 configurations.



Manganese(II) chloride can be prepared by treating manganese metal or manganese(II) carbonate with hydrogen chloride or hydrochloric acid, depending on whether one seeks the anhydrous or hydrated forms:

Mn + 2 HCl → MnCl2 + H2
MnCO3 + 2 HCl → MnCl2 + H2O + CO2

It also forms when manganese(IV) oxide is heated with concentrated hydrochloric acid; this reaction was once used for the manufacture of chlorine.

MnO2 + 4 HCl → MnCl2 + 2 H2O + Cl2

This reaction illustrates the oxidizing power of MnO2 and the fact that oxides tend to exist in higher oxidation states than chlorides.

Chemical properties

MnCl2 is a polymeric solid which adopts a layered structure. The hydrates dissolve in water to give mildly acidic solutions with a pH of around 4. Such aqueous solutions are used to prepare a variety of manganese compounds, e.g.,

MnCl2(aq) + K2CO3(aq) → MnCO3(s) + 2 KCl

In these equations, "MnCl2(aq)" refers to [Mn(H2O)6]2+, which is the principal form of manganese in aqueous solutions of any manganese chloride.

It is a weak Lewis acid, reacting with chloride ions to produce a series of solids containing the following ions [MnCl3]-, [MnCl4]2- , and [MnCl6]4-. Both [MnCl3]- and [MnCl4]2- are polymeric.

Upon treatment with typical organic ligands, manganese(II) undergoes oxidation by air to give Mn(III) complexes. Examples include [Mn(EDTA]-, [Mn(CN)6]3-, and [Mn(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 manganese compounds. For example, manganocene is prepared by reaction of MnCl2 with a solution of sodium cyclopentadienide in THF.

MnCl2 + 2 NaC5H5 → Mn(C5H5)2 + 2 NaCl


Manganese chloride is paramagnetic, this fact is utilized when MnCl2 is used as a contrast agent in MRI scanning. A dramatic example is using MnCl2 to highlight neural pathways.


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


  1. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
  2. Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990.
  3. A. F. Wells, 'Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
  4. The Merck Index, 7th edition, Merck & Co, Rahway, New Jersey, USA, 1960.
  5. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Manganese(II)_chloride". A list of authors is available in Wikipedia.
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