Editing Group 7 element (section)

=== Oxides ===

==== Manganese ====

[[File:Manganese(IV)_oxide.jpg|thumb|right|Manganese(IV) oxide]]

Manganese forms a variety of oxides: [[Manganese(II) oxide|MnO]], [[Manganese(II,III) oxide|Mn<sub>3</sub>O<sub>4</sub>]], [[Manganese(III) oxide|Mn<sub>2</sub>O<sub>3</sub>]], [[Manganese dioxide|MnO<sub>2</sub>]], MnO<sub>3</sub> and [[Manganese heptoxide|Mn<sub>2</sub>O<sub>7</sub>]]. Manganese(II) oxide is an inorganic compound that forms green crystals. Like many monoxides, MnO adopts the [[Cubic crystal system#Rock-salt structure|rock salt structure]], where cations and anions are both octahedrally coordinated. Also like many oxides, manganese(II) oxide is often [[nonstoichiometric]]: its composition can vary from MnO to MnO<sub>1.045</sub>.<ref name="G&W" />
Manganese(II,III) oxide is formed when any manganese oxide is heated in air above 1000&nbsp;°C.<ref name="G&W" /> Considerable research has centred on producing nanocrystalline Mn<sub>3</sub>O<sub>4</sub> and various syntheses that involve oxidation of Mn<sup>II</sup> or reduction of Mn<sup>VI</sup>.<ref>Hausmannite Mn<sub>3</sub>O<sub>4</sub> nanorods: synthesis, characterization and magnetic properties Jin Du et al.  Nanotechnology, (2006),17 4923-4928, {{doi| 10.1088/0957-4484/17/19/024}}</ref><ref>One-step synthesis of Mn<sub>3</sub>O<sub>4</sub> nanoparticles: Structural and magnetic study Vázquez-Olmos A.,  Redón R, Rodríguez-Gattorno G., Mata-Zamora M.E., Morales-Leal F, Fernández-Osorio A.L, Saniger J.M.   Journal of Colloid and Interface Science, 291, 1, (2005), 175-180 {{doi|10.1016/j.jcis.2005.05.005}}</ref><ref>{{Cite journal |last1=Sun |first1=Xiaoming |last2=Liu |first2=Junfeng |last3=Li |first3=Yadong |date=2006-02-20 |title=Use of Carbonaceous Polysaccharide Microspheres as Templates for Fabricating Metal Oxide Hollow Spheres |url=https://onlinelibrary.wiley.com/doi/10.1002/chem.200500660 |journal=Chemistry - A European Journal |language=en |volume=12 |issue=7 |pages=2039–2047 |doi=10.1002/chem.200500660 |pmid=16374888 |issn=0947-6539|url-access=subscription }}</ref> Manganese(III) oxide is unlike many other transition metal oxides in that it does not adopt the [[corundum]] ([[aluminium oxide|Al<sub>2</sub>O<sub>3</sub>]]) structure.<ref name="G&W" /> Two forms are generally recognized, α-Mn<sub>2</sub>O<sub>3</sub> and γ-Mn<sub>2</sub>O<sub>3</sub>,<ref name = "Wells">Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications {{ISBN|0-19-855370-6}}</ref> although a high pressure form with the CaIrO<sub>3</sub> structure has been reported too.<ref>High Pressure Phase transition in Mn<sub>2</sub>O<sub>3</sub> to the CaIrO<sub>3</sub>-type Phase Santillan, J.; Shim, S. American Geophysical Union, Fall Meeting 2005, abstract #MR23B-0050</ref> Manganese(IV) oxide is a blackish or brown solid occurs naturally as the mineral [[pyrolusite]], which is the main ore of manganese and a component of [[manganese nodule]]s. The principal use for MnO<sub>2</sub> is for dry-cell [[battery (electricity)|batteries]], such as the [[alkaline battery]] and the [[zinc–carbon battery]].<ref name="G&W" /> Manganese(VII) oxide is dark green in its [[crystalline]] form. The liquid is green by reflected light and red by transmitted light.<ref name=brauer>{{cite book|author=H. Lux|chapter=Manganese(VII) Oxide|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY, NY|volume=1|pages=1459–1460}}</ref> It is soluble in [[carbon tetrachloride]], and decomposes when in contact with water.

==== Technetium ====

[[File:Technetium(IV)_oxide.png|thumb|right|Technetium(IV) oxide]]

Technetium's main oxides are [[technetium(IV) oxide]] and [[technetium(VII) oxide]]. Technetium(IV) oxide was first produced in 1949 by electrolyzing a solution of [[ammonium pertechnetate]] under [[ammonium hydroxide]]. It has often been used to separate technetium from [[molybdenum]] and rhenium.<ref name="tc" /><ref name="radio" /><ref name="electro">{{cite journal |author1=L. B. Rogers |title=Electroseparation of Technetium from Rhenium and Molybdenum |journal=Journal of the American Chemical Society |date=1949 |volume=71 |issue=4 |pages=1507–1508 |doi=10.1021/ja01172a520 |language=en}}</ref> More efficient ways are the reduction of ammonium pertechnetate by [[zinc]] metal and [[hydrochloric acid]], [[stannous chloride]], [[hydrazine]], [[hydroxylamine]], [[ascorbic acid]],<ref name="radio">{{cite journal |author1=Edward Anders |title=THE RADIOCHEMISTRY OF TECHNETIUM |url=https://www.osti.gov/biblio/4073069 |website=OSTI.GOV |publisher=U.S. Department of Energy Office of Scientific and Technical Information |access-date=4 November 2022 |page=8 |doi=10.2172/4073069 |date=1960|osti=4073069 }}</ref> by the hydrolysis of [[potassium hexachlorotechnetate]]<ref name="magnet">{{cite journal |author1=C. M. Nelson |author2=G. E. Boyd |author3=Wm. T. Smith Jr. |title=Magnetochemistry of Technetium and Rhenium |journal=Journal of the American Chemical Society |date=1954 |volume=76 |issue=2 |pages=348–352 |doi=10.1021/ja01631a009 |publisher=ACS Publications |language=en}}</ref> or by the decomposition of ammonium pertechnetate at 700&nbsp;°C under an inert atmosphere.<ref name="tc">{{cite book |author1=A. G. Sharpe |author2=H. J. Emeléus |title=Advances in Inorganic Chemistry and Radiochemistry |date=1968 |publisher=Elsevier Science |isbn=9780080578606 |page=21 |url=https://books.google.com/books?id=-SnCsg5jM_kC&pg=PA21}}</ref><ref name="img">{{cite thesis |author1=Bradley Covington Childs |title=Volatile Technetium Oxides: Implications for Nuclear Waste Vitrification |journal=UNLV Theses, Dissertations, Professional Papers, and Capstones |date=2017 |doi=10.34917/10985836}}</ref><ref name="at">{{cite journal |author1=Edward Andrews |title=Technetium and Astatine Chemistry |journal=Annual Review of Nuclear Science |date=1959 |volume=9 |pages=203–220 |doi=10.1146/annurev.ns.09.120159.001223 |publisher=Annual Reviews |language=en|doi-access=free |bibcode=1959ARNPS...9..203A }}</ref> It reacts with oxygen to produce technetium(VII) oxide at 450&nbsp;°C.

Technetium(VII) oxide can be prepared directly by the oxidation of technetium at 450-500&nbsp;°C.<ref>{{cite book|author1=Herrell, A. Y. |author2=Busey, R. H. |author3=Gayer, K. H. | title = Technetium(VII) Oxide, in Inorganic Syntheses| year = 1977 | volume = XVII| pages = 155–158 | isbn = 0-07-044327-0|doi=10.1002/9780470132487.ch41}}</ref> It is a rare example of a molecular binary metal oxide. Other examples are [[ruthenium(VIII) oxide]] and [[osmium(VIII) oxide]]. It adopts a [[centrosymmetric]] corner-shared bi-tetrahedral structure in which the terminal and bridging  Tc&minus;O bonds are 167pm and 184 pm respectively and the Tc&minus;O&minus;Tc angle is 180°.<ref>{{cite journal|last=Krebs|first=Bernt|title = Technetium(VII)-oxid: Ein Übergangsmetalloxid mit Molekülstruktur im festen Zustand| journal = Angewandte Chemie | year = 1969 | volume = 81| issue = 9| pages = 328–329| doi = 10.1002/ange.19690810905|bibcode=1969AngCh..81..328K}}</ref>

==== Rhenium ====

Rhenium's main oxides are [[rhenium(IV) oxide]] and [[rhenium(VII) oxide]]. Rhenium(IV) oxide is a gray to black crystalline solid that can be formed by [[comproportionation]].<ref>G. Glemser "Rhenium (IV) Oxide" Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1480.</ref> At high temperatures it undergoes [[disproportionation]]. It is a laboratory reagent that can be used as a [[catalyst]]. It adopts the [[rutile structure]]. It forms [[perrhenate]]s with alkaline [[hydrogen peroxide]] and [[oxidizing acid]]s.<ref>{{cite web |url=http://www.aaamolybdenum.com/RheniumDioxide.html |title=RHENIUM DIOXIDE - Manufacturer |publisher=Aaamolybdenum.com |accessdate=2012-08-06 |url-status=dead |archiveurl=https://web.archive.org/web/20030209232809/http://www.aaamolybdenum.com/RheniumDioxide.html |archivedate=2003-02-09 }}</ref> In molten sodium hydroxide it forms sodium rhenate:<ref>G. Glemser "Sodium Rhenate (IV)" Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1483.</ref>

: 2{{nbsp}}NaOH  +  ReO<sub>2</sub>   →   Na<sub>2</sub>ReO<sub>3</sub>  +  H<sub>2</sub>O

Rhenium(VII) oxide can be formed when rhenium or its oxides or sulfides are oxidized a 500-700&nbsp;°C in air.<ref name=Schmidt>{{cite book |title=Inorganic Syntheses |year=1967 |volume=9 |last1=Schmidt |first1=Max |last2=Schmidbaur |first2=Hubert |chapter=Trimethylsilyl Perrhenate |pages=149–151 |isbn=9780470132401 |doi=10.1002/9780470132401.ch40}}</ref> It dissolves in water to give [[perrhenic acid]]. Heating Re<sub>2</sub>O<sub>7</sub> gives rhenium(IV) oxide, signalled by the appearance of the dark blue coloration.<ref name="Brauer" /> In its solid form, Re<sub>2</sub>O<sub>7</sub> consists of alternating octahedral and tetrahedral Re centres. It is the raw material for all rhenium compounds, being the volatile fraction obtained upon roasting the host ore.<ref>{{Ullmann|doi=10.1002/14356007.a23_199|title=Rhenium and Rhenium Compounds|year=2000|last1=Georg Nadler|first1=Hans|isbn=3527306730}}</ref>

Rhenium, in addition to the +4 and +7 oxidation states, also forms a [[rhenium trioxide|trioxide]]. It can be formed by reducing rhenium(VII) oxide with [[carbon monoxide]] at 200&nbsp;C or elemental rhenium at 4000&nbsp;C.<ref>{{Citation |last1=Nechamkin |first1=H. |title=Rhenium(VI) Oxide (Rhenium Trioxide) |date=Jan 1950|url=https://onlinelibrary.wiley.com/doi/10.1002/9780470132340.ch49 |work=Inorganic Syntheses |volume=3 |pages=186–188 |editor-last=Audrieth |editor-first=Ludwig F. |access-date=2023-08-26 |edition=1 |publisher=Wiley |language=en |doi=10.1002/9780470132340.ch49 |isbn=978-0-470-13162-6 |last2=Hiskey |first2=C. F. |last3=Moeller |first3=Therald |last4=Shoemaker |first4=C. E.|url-access=subscription }}</ref> It can also be reduced with [[dioxane]].<ref name="Glemser">{{cite book|author1=O. Glemser|author2=R. Sauer|chapter=Rhenium(VI) Oxide|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY, NY |volume=2 |pages=1482 }}</ref> It is a red solid with a metallic lustre that resembles [[copper]] in appearance, and is the only stable [[trioxide]] of the group 7 elements.