hyperchloride of manganese
3D model (JSmol)
|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
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|250-275 mg/kg (rat, oral)|
1715 mg/kg (mouse, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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 the tetrahydrate with the formula MnCl2·4H2O. The anhydrous form and a 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.
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.
- Mn + 2 HCl + 4 H2O → MnCl2(H2O)4 + H2
- MnCO3 + 2 HCl + 3 H2O → MnCl2(H2O)4 + CO2
Anhydrous MnCl2 adopts a layered cadmium chloride-like structure. The tetrahydrate consists of octahedral cis-Mn(H2O)4Cl2 molecules. The trans isomer, which is metastable, is also known. The dihydrate MnCl2(H2O)2 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.
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
Aqueous solutions of manganese(II) chloride are used in 31P-NMR to determine the size and lamellarity of phospholipid vesicles. 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 negligible for multilamellar vesicles, but for large unilamellar vesicles, a ~50% reduction in signal intensity is observed.
Manganism, or manganese poisoning, can be caused by long-term exposure to manganese dust or fumes.
- "Manganese compounds (as Mn)". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
- Reidies, Arno H. (2002), "Manganese Compounds", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a16_123, ISBN 3-527-30385-5.
- Zalkin, Allan; Forrester, J. D.; Templeton, David H. (1964). "Crystal structure of manganese dichloride tetrahydrate". Inorganic Chemistry. 3: 529–33. doi:10.1021/ic50014a017.
- A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
- Morosin, B.; Graeber, E. J. (1965). "Crystal structures of manganese(II) and iron(II) chloride dihydrate". Journal of Chemical Physics. 42: 898–901. doi:10.1063/1.1696078.
- 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, doi:10.1016/S0009-3084(00)00220-6, PMID 11163348
- Hope M, Bally M, Webb G, Cullis P (April 10, 1984), "Production of large unilamellar vesicles by a rapid extrusion procedure. Characterization of size distribution, trapped volume and ability to maintain a membrane potential" (PDF), Biochimica et Biophysica Acta, 812: 55–65, doi:10.1016/0005-2736(85)90521-8
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