Manganese(II) oxide

Manganese(II) oxide
IUPAC name Manganese(II) oxide
Other names Manganous oxide Manganosite manganese monoxide
Identifiers
CAS number	1344-43-0 Y
PubChem	14940
RTECS number	OP0900000
Properties
Molecular formula	MnO
Molar mass	70.9374 g/mol
Appearance	green crystalline
Density	5.37 g/cm3 (23 °C)
Melting point	1945 °C
Solubility in water	insoluble
Refractive index (nD)	2.16
Structure
Crystal structure	Halite (cubic), cF8
Space group	Fm3m, No. 225
Coordination geometry	Octahedral (Mn2+); octahedral (O2–)
Hazards
EU Index	Not listed
Flash point	Non-flammable
Related compounds
Other anions	Manganese difluoride Manganese(II) sulfide
Other cations	Iron(II) oxide
Related manganese oxides	Manganese(II,III) oxide Manganese(III) oxide Manganese dioxide Manganese heptoxide
Y oxide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Manganese(II) oxide is the inorganic compound with formula MnO.^[1] MnO is a basic oxide that is insoluble in water but dissolves in acids, forming manganese(II) salts.^[2]

Preparation and occurrence

MnO can be prepared by the reduction of any higher oxide with hydrogen^[2] e.g.:

MnO₂ + H₂ → MnO + H₂O

Commercially it is prepared by reduction of MnO₂ with hydrogen, carbon monoxide or methane:^[1]

MnO₂ + CO → MnO + CO₂

MnO can also be prepared by heating MnCO₃:^[3]

MnCO₃ → MnO + CO₂

This calcining process is conducted anaerobically to prevent formation of Mn₂O₃. MnO occurs in nature as the rare mineral manganosite.

Structure and properties

MnO has the NaCl, rock salt structure, where cations and anions are both octahedrally coordinated.^[2] The composition of MnO can vary from MnO to MnO_1.045.^[2]
Below 118 K MnO is antiferromagnetic.^[2] MnO has the distinction of being one of the first compounds^[4] to have its magnetic structure determined by neutron diffraction in 1951.^[5]. This study showed that the Mn²⁺ ions form a face centered cubic magnetic sub-lattice where there are ferromagnetically coupled sheets which are anti-parallel with adjacent sheets.

Applications

Together with manganese sulfate, MnO is a component of fertilizer and feed additives. Many thousands of tons are consumed annually for this purpose.^[1]

References

1. ^ ^{a b c} Arno H. Reidies "Manganese Compounds" Ullmann's Encyclopedia of Chemical Technology 2007; Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_123
2. ^ ^{a b c d e} Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 0080379419. 
3. ^ W.H. McCarroll (1994) Oxides- solid sate chemistry, Encyclopedia of Inorganic chemistry Ed. R. Bruce King, John Wiley & Sons ISBN 0-471-93620-0
4. ^ J.E Greedon, (1994), Magnetic oxides in Encyclopedia of Inorganic chemistry Ed. R. Bruce King, John Wiley & Sons ISBN 0-471-93620-0
5. ^ Neutron Diffraction by Paramagnetic and Antiferromagnetic Substances C. G. Shull, W. A. Strauser, and E. O. Wollan, Phys. Rev. 83, 333 - 345 (1951), doi:10.1103/PhysRev.83.333