Manganese(II) chloride
| 200px Anhydrous
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| 200px Tetrahydrate
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| Names | |
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| IUPAC names
Manganese(II) chloride
Manganese dichloride |
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| Other names
Manganous chloride
hyperchloride of managnese |
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| Identifiers | |
7773-01-5  38639-72-4 (dihydrate) 13446-34-9 (tetrahydrate) |
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| ChEMBL | ChEMBL1200693  |
| ChemSpider | 22888 |
| Jmol 3D model | Interactive image |
| PubChem | 24480 |
| RTECS number | OO9625000 |
| UNII | 6YB4901Y90 |
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| 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) |
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| Solubility | soluble in pyridine, ethanol insoluble in ether |
| Structure | |
| CdCl2 | |
| octahedral | |
| Vapor pressure | {{{value}}} |
| Related compounds | |
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Other anions
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Manganese(II) fluoride Manganese(II) bromide Manganese(II) iodide |
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Other cations
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Manganese(III) chloride Technetium(IV) chloride Rhenium(III) chloride Rhenium(IV) chloride Rhenium(V) chloride Rhenium(VI) chloride |
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Related compounds
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Chromium(II) chloride Iron(II) chloride |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 verify (what is ?) |
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| Infobox 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 the most common form of "manganese(II) chloride" and is represented by the formula MnCl2·4H2O, but the anhydrous form and dihydrate MnCl2·2H2O are also known. Like many Mn(II) species, these salts are pink, with the paleness of the color being characteristic of transition metal complexes with high spin d5 configurations.[1]
Contents
Preparation
Manganese chloride is produced by treating manganese(IV) oxide with concentrated hydrochloric acid.
- MnO2 + 4 HCl → MnCl2 + 2 H2O + Cl2
This reaction was once 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.[2]
In the laboratory, manganese chloride can be prepared by treating manganese metal or manganese(II) carbonate and hydrochloric acid:
- Mn + 2 HCl → MnCl2 + H2
- MnCO3 + 2 HCl → MnCl2 + H2O + CO2
Chemical properties
Anhydrous MnCl2 is a polymeric solid, which adopts a layered cadmium chloride-like structure. The tetrahydrate consists of octahedral trans-Mn(H2O)4Cl2 molecules[3] The hydrates dissolve in water to give mildly acidic solutions with a pH of around 4.
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
Applications
The main application is used in the production of dry cell batteries. It is the precursor to the antiknock compound methylcyclopentadienyl manganese tricarbonyl.[2]
Vesicle characterization with 31P-NMR
MnCl2 is used in 31P-NMR to determine the size and lamellarity of phospholipid vesicles.[4] When manganese chloride is added to a vesicular solution, Mn2+ paramagnetic ions are released, perturbing the relaxation time of the phospholipids' phosphate groups and broadening the resulting 31P resonance signal. Only phospholipids located in the outermost monolayer exposed to Mn2+ experience this broadening. The effect is negligle for multilamellar vesicles, but for large unilamellar vesicles, a ~50% reduction in signal intensity is observed.[5]
Precautions
Manganism, or manganese poisoning, can be caused by long-term exposure to manganese dust or fumes.
References
- ↑ N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
- ↑ 2.0 2.1 Lua error in package.lua at line 80: module 'strict' not found..
- ↑ A. F. Wells, 'Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
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External links
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- Chlorides
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- Metal halides
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