Manganese(II) oxide
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| IUPAC name
Manganese(II) oxide
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| Other names | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.014.269 |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| MnO | |
| Molar mass | 70.9374 g/mol |
| Appearance | green crystals or powder |
| Density | 5.43 g/cm3 |
| Melting point | 1,945 °C (3,533 °F; 2,218 K) |
| insoluble | |
| Solubility | soluble in acid |
| +4850.0·10−6 cm3/mol | |
Refractive index (nD)
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2.16 |
| Structure | |
| Halite (cubic), cF8 | |
| Fm3m, No. 225 | |
| Octahedral (Mn2+); octahedral (O2−) | |
| Thermochemistry | |
Std molar
entropy (S⦵298) |
60 J·mol−1·K−1[1] |
Std enthalpy of
formation (ΔfH⦵298) |
−385 kJ·mol−1[1] |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Related compounds | |
Other anions
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Manganese(II) fluoride Manganese(II) sulfide Manganese(II) selenide Manganese(II) telluride |
Other cations
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Iron(II) oxide |
| Manganese(II,III) oxide Manganese(III) oxide Manganese dioxide Manganese heptoxide | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Manganese(II) oxide is an inorganic compound with chemical formula MnO.[2] It forms green crystals. The compound is produced on a large scale as a component of fertilizers and food additives.
Structure, stoichiometry, reactivity
Like many metal monoxides, MnO adopts the rock salt structure, where cations and anions are both octahedrally coordinated. Also like many metal oxides, manganese(II) oxide is often nonstoichiometric: its composition can vary from MnO to MnO1.045.[3]
Manganese(II) oxide undergoes the chemical reactions typical of an ionic oxide. Upon treatment with acids, it converts to the corresponding manganese(II) salt.[3] Oxidation of manganese(II) oxide gives manganese(III) oxide.
Preparation and occurrence
MnO occurs in nature as the rare mineral manganosite.
It is prepared commercially by reduction of MnO2 with hydrogen, carbon monoxide, or methane, e.g.:[2]
- MnO2 + H2 → MnO + H2O
- MnO2 + CO → MnO + CO2
Upon heating to 450 °C, manganese(II) nitrate gives a mixture of oxides, denoted MnO2−x, which can be reduced to the monoxide with hydrogen at ≥750 °C.[4] MnO is particularly stable and resists further reduction.[5] MnO can also be prepared by heating the carbonate:[6]
- MnCO3 → MnO + CO2
This calcining process is conducted anaerobically, lest Mn2O3 form.
An alternative route, most interest for demonstration purposes, is the "oxalate method". Also applicable to the synthesis of ferrous oxide and stannous oxide, it entails heating in an oxygen-free atmosphere (often CO2), hydrated manganese(II) oxalate:[7]
- MnC2O4·2H2O → MnO + CO2 + CO + 2 H2O
Applications
Together with manganese sulfate, MnO is a component of fertilizers and food additives. Many thousands of tons are consumed annually for this purpose. Other uses include: a catalyst in the manufacture of allyl alcohol, pigmenting ceramics and paints, coloring glass, bleaching tallow, and textile printing.[2]
Magnetism
Below 118 K, MnO is antiferromagnetic.[3] MnO has the distinction of being one of the first compounds[8] to have its magnetic structure determined by neutron diffraction, the report appearing in 1951.[9] This study showed that the Mn2+ ions form a face centered cubic magnetic sub-lattice where there are ferromagnetically coupled sheets that are anti-parallel with adjacent sheets.
Electronic structure
Similar to NiO, MnO is classed as a strongly correlated material because of the localised 3d states associated with Mn atoms, and is an electrical insulator.[10][11] Conventional approximations to the exchange-correlation functional in density functional theory (DFT) such as the local spin-density approximation (LSDA) severely underestimate the band gap of the material, and can even predict it to be metallic, depending on the choice of magnetic configuration.[10][12] However, improved descriptions of the material's electronic structure, such as hybrid exchange-correlation functionals, DFT+U[13], the GW approximation[12], self-interaction corrected DFT[14], or coupled cluster theory[15], all recover the band gap with significantly improved accuracy. It has also been shown that such improved methods predict a band gap regardless of the choice of magnetic state.[16]
References
- ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 978-0-618-94690-7.
- ^ a b c Arno H. Reidies "Manganese Compounds" Ullmann's Encyclopedia of Chemical Technology 2007; Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_123
- ^ a b c Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
- ^ H. Lux (1963). "Manganeses(II) Oxide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2. NY, NY: Academic Press. p. 1455.
- ^ Wellbeloved, David B.; Craven, Peter M.; Waudby, John W. (2000). "Manganese and Manganese Alloys". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a16_077. ISBN 3-527-30673-0.
- ^ W.H. McCarroll (1994) Oxides- Solid State Chemistry, Encyclopedia of Inorganic Chemistry Ed. R. Bruce King, John Wiley & Sons ISBN 0-471-93620-0
- ^ Arthur Sutcliffe (1930) Practical Chemistry for Advanced Students (1949 Ed.), John Murray - London.
- ^ J.E Greedon, (1994), Magnetic oxides in Encyclopedia of Inorganic chemistry Ed. R. Bruce King, John Wiley & Sons ISBN 0-471-93620-0
- ^ Shull, C. G.; Strauser, W. A.; Wollan, E. O. (1951-07-15). "Neutron Diffraction by Paramagnetic and Antiferromagnetic Substances". Physical Review. 83 (2). American Physical Society (APS): 333–345. Bibcode:1951PhRv...83..333S. doi:10.1103/physrev.83.333. ISSN 0031-899X.
- ^ a b Pask, J. E.; Singh, D. J.; Mazin, I. I.; Hellberg, C. S.; Kortus, J. (2001-06-11). "Structural, electronic, and magnetic properties of MnO". Physical Review B. 64 (2). arXiv:cond-mat/0012340. doi:10.1103/PhysRevB.64.024403. ISSN 0163-1829.
- ^ Terakura, K.; Williams, A. R.; Oguchi, T.; Kübler, J. (1984-05-14). "Transition-Metal Monoxides: Band or Mott Insulators". Physical Review Letters. 52 (20): 1830–1833. doi:10.1103/PhysRevLett.52.1830. ISSN 0031-9007.
- ^ a b Faleev, Sergey V.; van Schilfgaarde, Mark; Kotani, Takao (2004-09-17). "All-Electron Self-Consistent G W Approximation: Application to Si, MnO, and NiO". Physical Review Letters. 93 (12). arXiv:cond-mat/0310677. doi:10.1103/PhysRevLett.93.126406. ISSN 0031-9007.
- ^ Trimarchi, Giancarlo; Wang, Zhi; Zunger, Alex (2018-01-05). "Polymorphous band structure model of gapping in the antiferromagnetic and paramagnetic phases of the Mott insulators MnO, FeO, CoO, and NiO". Physical Review B. 97 (3). arXiv:1709.02494. doi:10.1103/PhysRevB.97.035107. ISSN 2469-9950.
- ^ Däne, M; Lüders, M; Ernst, A; Ködderitzsch, D; Temmerman, W M; Szotek, Z; Hergert, W (2009-01-28). "Self-interaction correction in multiple scattering theory: application to transition metal oxides". Journal of Physics: Condensed Matter. 21 (4) 045604. doi:10.1088/0953-8984/21/4/045604. ISSN 0953-8984.
- ^ Gao, Yang; Sun, Qiming; Yu, Jason M.; Motta, Mario; McClain, James; White, Alec F.; Minnich, Austin J.; Chan, Garnet Kin-Lic (2020-04-27). "Electronic structure of bulk manganese oxide and nickel oxide from coupled cluster theory". Physical Review B. 101 (16). arXiv:1910.02191. doi:10.1103/PhysRevB.101.165138. ISSN 2469-9950.
- ^ Hughes, I D; Däne, M; Ernst, A; Hergert, W; Lüders, M; Staunton, J B; Szotek, Z; Temmerman, W M (2008-06-06). "Onset of magnetic order in strongly-correlated systems from ab initio electronic structure calculations: application to transition metal oxides". New Journal of Physics. 10 (6) 063010. arXiv:0802.3660. doi:10.1088/1367-2630/10/6/063010. ISSN 1367-2630.