:Manganese(II) oxide

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 MnO_1.045.{{Greenwood&Earnshaw2nd}}

Below 118 K, MnO is antiferromagnetic. MnO has the distinction of being one of the first compoundsJ.E Greedon, (1994), Magnetic oxides in Encyclopedia of Inorganic chemistry Ed. R. Bruce King, John Wiley & Sons {{ISBN|0-471-93620-0}} to have its magnetic structure determined by neutron diffraction, the report appearing in 1951.{{cite journal | last1=Shull | first1=C. G. | last2=Strauser | first2=W. A. | last3=Wollan | first3=E. O. | title=Neutron Diffraction by Paramagnetic and Antiferromagnetic Substances | journal=Physical Review | publisher=American Physical Society (APS) | volume=83 | issue=2 | date=1951-07-15 | issn=0031-899X | doi=10.1103/physrev.83.333 | pages=333–345| bibcode=1951PhRv...83..333S }} 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.

Manganese(II) oxide undergoes the chemical reactions typical of an ionic oxide. Upon treatment with acids, it converts to the corresponding manganese(II) salt. Oxidation of manganese(II) oxide gives manganese(III) oxide.

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.:

:MnO₂ + H₂ → MnO + H₂O

:MnO₂ + CO → MnO + CO₂

Upon heating to 450{{nbsp}}°C, manganese(II) nitrate gives a mixture of oxides, denoted MnO_2−x, which can be reduced to the monoxide with hydrogen at ≥750{{nbsp}}°C.{{cite book|author1=H. Lux|chapter=Manganeses(II) Oxide|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY, NY|volume=2pages=1455}}

MnO is particularly stable and resists further reduction.{{cite book |doi=10.1002/14356007.a16_077|chapter=Manganese and Manganese Alloys |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2000 |last1=Wellbeloved |first1=David B. |last2=Craven |first2=Peter M. |last3=Waudby |first3=John W. |isbn=3527306730 }}

MnO can also be prepared by heating the carbonate:W.H. McCarroll (1994) Oxides- Solid State Chemistry, Encyclopedia of Inorganic Chemistry Ed. R. Bruce King, John Wiley & Sons {{ISBN|0-471-93620-0}}

: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:Arthur Sutcliffe (1930) Practical Chemistry for Advanced Students (1949 Ed.), John Murray - London.

:MnC₂O₄·2H₂O → MnO + CO₂ + CO + 2 H₂O

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, ceramics, paints, colored glass, bleaching tallow and textile printing.

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{{Manganese compounds}}

{{oxides}}

Category:Manganese(II) compounds

Category:Transition metal oxides

Category:Rock salt crystal structure