Manganese heptoxide: Difference between revisions

| verifiedrevid = 431916363

| Name = Manganese(VII) oxide

| ImageFile1 = Mn2O7.png

| ImageSize1 =

| ImageName1 = Manganese(VII) oxide

| ImageFile2 = Manganese-heptoxide-3D-balls.png

| ImageSize2 =

| ImageName2 = Ball-and-stick model of manganese heptoxide

| ImageFile3 = Manganese heptoxide.jpg

| ImageName3 = Manganese(VII) oxide

| IUPACName = Manganese(VII) oxide

| OtherNames = Permanganic acid<br />Manganic oxide<br /> dimanganese heptoxide

| Section1 = {{Chembox Identifiers

| SMILES = O=(O=)(O=)MnOMn(=O)(=O)=O

| CASNo = 12057-92-0

| RTECS =

}}

| Section2 = {{Chembox Properties

| Formula = Mn₂O₇

| MolarMass = 221.87 g/mol

| Appearance = dark red oil (room temp.), green if in contact with sulfuric acid

| Density = 2.79 g/cm³

| Solubility = decomposes to permanganic acid, HMnO4

| MeltingPt = 5.9 °C, 279.1 K

| BoilingPt = explodes on heating<br /> sublimes at −10 °C

}}

| Section3 = {{Chembox Structure

| Coordination = bitetrahedral

| CrystalStruct = monoclinic

}}

| Section7 = {{Chembox Hazards

| ExternalMSDS =

| MainHazards = explosive, strong oxidizer, very corrosive

| RPhrases =

| SPhrases =

}}

| Section8 = {{Chembox Related

| OtherCpds = [[Rhenium(VII) oxide|Re₂O₇<br />]] [[Potassium permanganate|KMnO₄]]<br /> [[Technetium(VII) oxide|Tc₂O₇]]

}}

'''Manganese(VII) oxide''' is an [[inorganic compound]] with the [[chemical formula|formula]] Mn₂O₇. This volatile liquid is highly reactive and more often discussed than intentionally prepared. It is a dangerous oxidizer and was first described in 1860.<ref>Aschoff, H. Ann. Phys. Chem. Ser. 2 volume 111 (1860) page 217 and page 224.</ref>

The [[crystalline]] form of this chemical compound is dark green. It is soluble in [[carbon tetrachloride]], and decomposes when in contact with water. It melts at only 5.9 °C, and sublimes at −10 °C{{Clarify|date=June 2010}}. These properties indicate a [[Polarity (chemistry)|nonpolar]] molecular species, which is confirmed by its structure. The molecules consist of a pair of tetrahedra 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°.<ref>{{cite journal | author = Simon, A.; Dronskowski, R.; Krebs, B.; Hettich, B. | title = The Crystal Structure of Mn₂O₇ | journal = [[Angew. Chem. Int. Ed. Engl.]] | year = 1987 | volume = 26 | pages = 139–140 | doi = 10.1002/anie.198701391}}</ref>

It contains manganese in its highest oxidation state. This oxidation state, +7, is shared by [[permanganate]]s, which are more stable compounds.

Pyrosulfate, pyrophosphate, and dichromate adopt structures similar to that of Mn₂O₇. Probably the most similar main group species is [[dichlorine heptoxide|Cl₂O₇]]. Focusing on comparisons within the transition metal series, [[technetium(VII) oxide|Tc₂O₇]] and Mn₂O₇ are structurally similar but the Tc-O-Tc angle is 180°. Solid [[rhenium(VII) oxide|Re₂O₇]] is not molecular but consists of crosslinked Re centers with both tetrahedral and octahedral sites,<ref>{{cite journal | author = Krebs, B.; Mueller, A.; Beyer, H. H. | title = The Crystal Structure of Rhenium(VII) Oxide | journal = [[Inorganic Chemistry (journal)|Inorganic Chemistry]] | year = 1969 | volume = 8 | pages = 436–443 | doi = 10.1021/ic50073a006}}</ref> in the vapour phase it is molecular with a similar structure to Tc₂O₇.<ref>Wells A.F. (1962) ''Structural Inorganic Chemistry'' 3d edition Oxford University Press</ref>

Mn₂O₇ arises as a dark green oil by the addition of concentrated [[sulfuric acid|H₂SO₄]] to [[potassium permanganate|KMnO₄]]. The reaction initially produces permanganic acid, HMnO₄ (structurally, HOMnO₃), which is dehydrated by sulfuric acid to form its [[anhydride]], Mn₂O₇.

:2 KMnO₄ +(cold) 2 H₂SO₄ → Mn₂O₇ + H₂O + 2 KHSO₄

Mn₂O₇ can react further with sulfuric acid to give the remarkable cation MnO₃⁺, which is [[isoelectronicity|isoelectronic]] with [[chromium trioxide|CrO₃]]:{{Citation needed|date=June 2010}}

:Mn₂O₇ + 2 H₂SO₄ → 2 {{chem|[MnO|3|]|+|[HSO|4|]|-}} + H₂O

Mn₂O₇ decomposes near room temperature, explosively so at &gt; 55 °C. The explosion can be initiated by striking the sample or by its exposure to oxidizable organic compounds. The products are [[manganese dioxide|MnO₂]] and [[oxygen|O₂]].<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref> [[Ozone]] is also produced, giving a strong smell to the substance. The ozone can spontaneously ignite a piece of paper impregnated with an alcohol solution. The production of manganese heptoxide is an undesirable byproduct in many situations.{{Citation needed|date=September 2011}}

[[Category:Manganese compounds]]

[[Category:Oxides]]

[[cs:Oxid manganistý]]

[[de:Mangan(VII)-oxid]]

[[fr:Heptoxyde de dimanganèse]]

[[it:Eptossido di dimanganese]]

[[pl:Tlenek manganu(VII)]]

[[pt:Óxido de manganês (VII)]]

[[ru:Оксид марганца(VII)]]

[[simple:Manganese(VII) oxide]]

[[sk:Oxid manganistý]]

[[sv:Mangan(VII)oxid]]

[[zh:七氧化二锰]]