Manganese heptoxide

<h2 id="properties">Properties</h2>
<p>The <a href="/facts/Crystalline/e2R2mk3E">crystalline</a> form of this chemical compound is dark green. The liquid is green by reflected light and red by transmitted light.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> It is soluble in <a href="/facts/Carbon_tetrachloride/S2ekjT0E">carbon tetrachloride</a>, and decomposes when in contact with water.
</p>
<h2 id="structure">Structure</h2>
<p>Its solubility properties indicate a <a href="/facts/Polarity_(chemistry)/KlIJ0zjB">nonpolar</a> molecular species, which is confirmed by its structure. The molecules consist of a pair of <a href="/facts/Tetrahedra/7mkSrl6j">tetrahedra</a> that share a common vertex. The vertices are occupied by oxygen atoms and at the centers of the tetrahedra are the Mn(VII) centers. The connectivity is indicated by the formula O3Mn−O−MnO3. The terminal Mn−O distances are 1.585 Å and the bridging oxygen is 1.77 Å distant from the two Mn atoms. The Mn−O−Mn angle is 120.7°.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p><p><a href="/facts/Pyrosulfate/PoR7hg9y">Pyrosulfate</a>, <a href="/facts/Pyrophosphate/L9FPEkhF">pyrophosphate</a>, and <a href="/facts/Dichromate/6xkFLIJw">dichromate</a> adopt structures similar to that of Mn2O7. Probably the most similar main group species is <a href="/facts/Dichlorine_heptoxide/YqfYHlzE">Cl2O7</a>. Focusing on comparisons within the transition metal series, <a href="/facts/Technetium(VII)_oxide/T7QzeaBh">Tc2O7</a> and Mn2O7 are structurally similar but the Tc−O−Tc angle is 180°. Solid <a href="/facts/Rhenium(VII)_oxide/QBUcnAeD">Re2O7</a> is not molecular but consists of crosslinked Re centers with both tetrahedral and octahedral sites;<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> in the vapour phase it is molecular with a similar structure to Tc2O7.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
</p>
<h2 id="synthesis-and-reactions">Synthesis and reactions</h2>
<p>Mn2O7 arises as a dark green oil by the addition of cold concentrated <a href="/facts/Sulfuric_acid/Wom6fymJ">H2SO4</a> to solid <a href="/facts/Potassium_permanganate/nyjjuDlo">KMnO4</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> The reaction initially produces <a href="/facts/Permanganic_acid/x8WPd8kw">permanganic acid</a>, HMnO4 (structurally, HOMnO3), which is dehydrated by cold sulfuric acid to form its <a href="/facts/Anhydride/9YnWCsJo">anhydride</a>, Mn2O7:
</p>
2 KMnO4 + 2 H2SO4  →  Mn2O7 + H2O + 2 KHSO4
<p>Mn2O7 can react further with sulfuric acid to give the remarkable manganyl(VII) cation MnO+3, which is <a href="/facts/Isoelectronicity/SbzuaI05">isoelectronic</a> with <a href="/facts/Chromium_trioxide/ENafKcAm">CrO3</a>:
</p>
Mn2O7 + 2 H2SO4  →  2 [MnO3]+[HSO4]− + H2O
<p>Mn2O7 decomposes near room temperature, explosively so above 55 °C (131 °F). The explosion can be initiated by striking the sample or by its exposure to oxidizable organic compounds. The products are <a href="/facts/Manganese_dioxide/HRwgXlUe">MnO2</a> and <a href="/facts/Oxygen/acyn6o8r">O2</a>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> <a href="/facts/Ozone/o0E5gn2p">Ozone</a> is also produced, giving a strong smell to the substance. The ozone can spontaneously ignite a piece of paper impregnated with an alcohol solution.
</p><p>Manganese heptoxide reacts with <a href="/facts/Hydrogen_peroxide/vju6HBIc">hydrogen peroxide</a> in presence of <a href="/facts/Sulfuric_acid/Wom6fymJ">sulfuric acid</a>, liberating <a href="/facts/Oxygen/acyn6o8r">oxygen</a> and <a href="/facts/Ozone/o0E5gn2p">ozone</a>:
</p>
2 Mn2O7 + 2 <a href="/facts/Hydrogen_peroxide/vju6HBIc">H2O2</a> + 4 <a href="/facts/Sulfuric_acid/Wom6fymJ">H2SO4</a>  →  4 <a href="/facts/Manganese(II)_sulfate/RVBG26R6">MnSO4</a> + 6 <a href="/facts/Water/0lkXnJPK">H2O</a> + 2 <a href="/facts/Ozone/o0E5gn2p">O3</a> + 3 <a href="/facts/Oxygen/acyn6o8r">O2</a>

<h2 id="external-links">External links</h2>
<p><a href="https://www.youtube.com/watch?v=2BZGjycR7YM">Demonstration of manganese heptoxide's properties</a> on <a href="/facts/YouTube/db276jst">YouTube</a></p>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Aschoff, H. Ann. Phys. Chem. Ser. 2 volume 111 (1860) page 217 and page 224. <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>H. Lux (1963). "Manganese(VII) Oxide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. pp. 1459–1460. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Simon, A.; Dronskowski, R.; Krebs, B.; Hettich, B. (1987). "The Crystal Structure of Mn2O7". Angew. Chem. Int. Ed. Engl. 26 (2): 139–140. doi:10.1002/anie.198701391. <a href="/wiki/Angew._Chem._Int._Ed._Engl." target="_blank">/wiki/Angew._Chem._Int._Ed._Engl.</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Krebs, B.; Mueller, A.; Beyer, H. H. (1969). "The Crystal Structure of Rhenium(VII) Oxide". Inorganic Chemistry. 8 (3): 436–443. doi:10.1021/ic50073a006. <a href="/wiki/Inorganic_Chemistry_(journal)" target="_blank">/wiki/Inorganic_Chemistry_(journal)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Wells A.F. (1962) Structural Inorganic Chemistry 3d edition Oxford University Press <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>H. Lux (1963). "Manganese(VII) Oxide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. pp. 1459–1460. <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
</ol>

Manganese heptoxide open-in-new

Manganese heptoxide