Manganese(II) iodide

Manganese(II) iodide is the chemical compound composed of manganese and iodide with the formula MnI₂(H2O)_n. The tetrahydrate is a pink solid while the anhydrous derivative is beige.^[2] Both forms feature octahedral Mn centers. Unlike MnCl₂(H₂O)₄ and MnBr₂(H₂O)₄ which are cis, MnI₂(H₂O)₄ is trans.^[3]

Manganese(II) iodide

Ball-and-stick model of part of a layer in the crystal structure of manganese(II) iodide
Ball-and-stick model of layer stacking in the crystal structure of manganese(II) iodide
Molecular structure of manganese(II) iodide tetrahydrate
Names
IUPAC name Manganese(II) iodide
Identifiers
CAS Number	7790-33-2 Y 7790-33-2 tetrahydrate
3D model (JSmol)	Interactive image
ChemSpider	74227 Y
ECHA InfoCard	100.029.274
EC Number	232-201-6
PubChem CID	82250
UNII	5Q9VVO3QCN Y
CompTox Dashboard (EPA)	DTXSID20999088
InChI InChI=1S/2HI.Mn/h2*1H;/q;;+2/p-2 N Key: QWYFOIJABGVEFP-UHFFFAOYSA-L N InChI=1/2HI.Mn/h2*1H;/q;;+2/p-2 Key: QWYFOIJABGVEFP-NUQVWONBAL
SMILES [Mn+2].[I-].[I-]
Properties
Chemical formula	MnI2
Molar mass	308.747 g/mol
Appearance	pink crystalline
Density	5.01 g/cm3
Melting point	701 °C (1,294 °F; 974 K) (anhydrous) 80 °C (tetrahydrate)
Boiling point	1,033 °C (1,891 °F; 1,306 K)
Solubility in water	soluble
Magnetic susceptibility (χ)	+14,400·10−6 cm3/mol
Structure
Crystal structure	Rhombohedral, hP3, SpaceGroup = P-3m1, No. 164
Coordination geometry	octahedral
Hazards[1]
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H360
Precautionary statements	P201, P202, P281, P308+P313, P405, P501
NFPA 704 (fire diamond)	1 0 1
Flash point	non-flammable
Related compounds
Other anions	Manganese(II) fluoride Manganese(II) chloride Manganese(II) bromide
Other cations	Iron(II) iodide Cobalt(II) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation

Anhydrous MnI₂ is prepared from the elements:^[4]

Mn + I₂ → MnI₂

The tetrahydrate can be prepared by treating manganese(II) carbonate with hydriodic acid. The anhydrous form can be produced from it by dehydration in a vacuum.^[2]

Properties

Samples turn brown in air under the influence of light as a result of the oxidation of the iodide ion to iodine.^[5] It has a trigonal crystal structure of the cadmium iodide type (polytype 2H)^[6][7] with the space group P3m1 (space group no. 164). It dissolves in water and decomposes.^[5] The tetrahydrate has a monoclinic crystal structure with the space group P2₁/c (No. 14).^[3]

Applications

It is often used in the lighting industry.^[8]

References

1. "223646 Manganese(II) iodide 98%". Sigma-Aldrich. Retrieved 2011-08-05.
2. Hosseiny, Afshin; MacKie, Anthony G.; McAuliffe, Charles A.; Minten, Karl (1981). "The Coordination Chemistry of Manganese". Inorganica Chimica Acta. 49: 99–105. doi:10.1016/S0020-1693(00)90464-X.
3. Moore, J. E.; Abola, J. E.; Butera, R. A. (1985-09-15). "Structure of manganese(II) iodide tetrahydrate, MnI2.4H2O". Acta Crystallographica Section C: Crystal Structure Communications. 41 (9): 1284–1286. doi:10.1107/S0108270185007466. ISSN 0108-2701.
4. Friour, G.; Cahiez, G.; Normant, J. F. (1984). "Organomanganous Reagents; IX. Preparation of Various Halogenated, Alkoxylated, Aryloxylated, and Arylsulfenylated Ketones from Correspondingly Functionalized Carboxylic Acid Chlorides or Anhydrides". Synthesis. 1984: 37–40. doi:10.1055/s-1984-30724. S2CID 94812612.
5. Ans, Jan d'; Ans, Jan d' (1998). Elemente, anorganische Verbindungen und Materialien. Taschenbuch für Chemiker und Physiker / D'Ans (4., neubearb. u. rev. Aufl ed.). Ort nicht ermittelbar: Verlag nicht ermittelbar. ISBN 978-3-540-60035-0.
6. Riedel, Erwin; Alsfasser, Ralf, eds. (2007). Moderne anorganische Chemie: mit CD-ROM (3. Aufl ed.). Berlin: de Gruyter. ISBN 978-3-11-019060-1.
7. Cable, J. W.; Wilkinson, M. K.; Wollan, E. O.; Koehler, W. C. (1962). "Neutron Diffraction Investigation of the Magnetic Order in MnI₂". Phys. Rev. 125 (6): 1860–1864. doi:10.1103/PhysRev.125.1860.
8. Cepanec, Ivica (2004). Synthesis of Biaryls. Elsevier. p. 104. ISBN 0-08-044412-1. Retrieved 2008-06-18.