Editing Group 7 element (section)

=== Organometallic compounds ===

==== Manganese ====

{{Main article|Organomanganese chemistry}}

Organomanganese compounds were first reported in 1937 by Gilman and Bailee who described the reaction of [[phenyllithium]] and [[manganese(II) iodide]] to form phenylmanganese iodide (PhMnI) and diphenylmanganese (Ph<sub>2</sub>Mn).<ref name="Cahiez2009">{{cite journal|title=Chemistry of Organomanganese(II) Compounds|first1=Gerard|last1=Cahiez|first2=Christophe|last2=Duplais|first3=Julien|last3=Buendia|journal=[[Chem. Rev.]]|year=2009|volume=109 |issue=3 |pages=1434–1476 |doi=10.1021/cr800341a|pmid=19209933 }}</ref>

Following this precedent, other organomanganese halides can be obtained by alkylation of [[manganese(II) chloride]], [[manganese(II) bromide]], and [[manganese(II) iodide]].  Manganese iodide is attractive because the anhydrous compound can be prepared in situ from manganese and [[iodine]] in [[diethyl ether|ether]]. Typical alkylating agents are [[organolithium]] or [[organomagnesium]] compounds.

The chemistry of organometallic compounds of Mn(II) are unusual among the [[transition metal]]s due to the high ionic character of the Mn(II)-C bond.<ref>{{cite journal|first=Richard A.|last=Layfield|title=Manganese(II): The Black Sheep of the Organometallic Family|journal=[[Chem. Soc. Rev.]]|year=2008 |volume=37|issue=6|pages=1098–1107 |doi=10.1039/b708850g |pmid=18497923 }}</ref> The reactivity of organomanganese compounds can be compared to that of [[Organomagnesium chemistry|organomagnesium]] and [[organozinc compound]]s. The [[electronegativity]] of Mn (1.55) is comparable to that of Mg (1.31) and Zn (1.65), making the carbon atom (EN = 2.55) [[nucleophilic]]. The [[reduction potential]] of Mn is also intermediate between Mg and Zn.

==== Technetium ====

{{Main article|Organotechnetium chemistry}}

[[File:Tc CNCH2CMe2(OMe) 6Cation.png|thumb|right|[[Technetium (99mTc) sestamibi]] ("Cardiolite") is widely used for imaging of the heart.]]
Technetium forms a variety of [[coordination complex]]es with organic ligands. Many have been well-investigated because of their relevance to [[nuclear medicine]].<ref>{{cite journal|doi=10.1021/cr1000755|pmid=20415476|title=Technetium and Gallium Derived Radiopharmaceuticals: Comparing and Contrasting the Chemistry of Two Important Radiometals for the Molecular Imaging Era|journal=Chemical Reviews|volume=110|issue=5|pages=2903–20|year=2010|last1=Bartholomä|first1=Mark D.|last2=Louie|first2=Anika S.|last3=Valliant|first3=John F.|last4=Zubieta|first4=Jon}}</ref>

Technetium forms a variety of compounds with Tc–C bonds, i.e. organotechnetium complexes. Prominent members of this class are complexes with CO, arene, and cyclopentadienyl ligands.<ref name="Alberto" /> The binary carbonyl Tc<sub>2</sub>(CO)<sub>10</sub> is a white volatile solid.<ref>{{cite journal|doi = 10.1021/ja01474a038|date = 1961|last1 = Hileman|first1 = J. C.|last2 = Huggins|last3 = Kaesz|journal = Journal of the American Chemical Society |volume = 83|title = Technetium carbonyl|pages = 2953–2954|first2 = D. K.|first3 = H. D.|issue = 13}}</ref> In this molecule, two technetium atoms are bound to each other; each atom is surrounded by [[octahedron|octahedra]] of five carbonyl ligands. The bond length between technetium atoms, 303&nbsp;pm,<ref>{{cite journal|title = The Crystal Structure of Ditechnetium Decacarbonyl|doi =10.1021/ic50030a011|date =1965|last1 =Bailey|first1 = M. F.|journal =Inorganic Chemistry|volume =4|pages =1140–1145|last2 = Dahl|first2 = Lawrence F.|issue = 8}}</ref><ref>{{cite journal|doi = 10.1107/S0365110X62002789|title = Unit cell and space group of technetium carbonyl, Tc2(CO)10|date = 1962|last1 = Wallach|first1 = D.|journal = Acta Crystallographica|volume = 15|page = 1058|issue = 10| bibcode=1962AcCry..15.1058W }}</ref> is significantly larger than the distance between two atoms in metallic technetium (272&nbsp;pm). Similar [[carbonyl]]s are formed by technetium's [[Congener (chemistry)|congeners]], manganese and rhenium.{{sfn|Schwochau|2000|pp=286, 328}} Interest in organotechnetium compounds has also been motivated by applications in [[nuclear medicine]].<ref name="Alberto">{{cite book|doi=10.1007/978-3-642-13185-1_9|chapter=Organometallic Radiopharmaceuticals|title=Medicinal Organometallic Chemistry|volume=32|pages=219–246|series=Topics in Organometallic Chemistry|year=2010 |last1=Alberto|first1=Roger|isbn=978-3-642-13184-4}}</ref> Unusual for other metal carbonyls, Tc forms aquo-carbonyl complexes, prominent being [Tc(CO)<sub>3</sub>(H<sub>2</sub>O)<sub>3</sub>]<sup>+</sup>.<ref name="Alberto" />

==== Rhenium ====

{{Main article|Organorhenium chemistry}}

[[Dirhenium decacarbonyl]] is the most common entry to organorhenium chemistry. Its reduction with sodium [[Amalgam (chemistry)|amalgam]] gives Na[Re(CO)<sub>5</sub>] with rhenium in the formal oxidation state −1.<ref>{{cite journal|doi = 10.1002/cber.19901230103|title = Nucleophile Addition von Carbonylmetallaten an kationische Alkin-Komplexe [CpL2M(η2-RC≡CR)]+ (M = Ru, Fe): μ-η1:η1-Alkin-verbrückte Komplexe|date = 1990|author = Breimair, Josef|journal = Chemische Berichte|volume = 123|page = 7|last2 = Steimann|first2 = Manfred|last3 = Wagner|first3 = Barbara|last4 = Beck|first4 = Wolfgang}}</ref> Dirhenium decacarbonyl can be oxidised with [[bromine]] to [[bromopentacarbonylrhenium(I)]]:<ref>{{cite book|title=Inorganic Syntheses|first=Steven P.|last =Schmidt|author2=Trogler, William C. |author3=Basolo, Fred |chapter=Pentacarbonylrhenium Halides | volume=28|date=1990|pages=154–159|doi=10.1002/9780470132593.ch42|isbn=978-0-470-13259-3}}</ref>
:Re<sub>2</sub>(CO)<sub>10</sub> + Br<sub>2</sub> → 2 Re(CO)<sub>5</sub>Br

Reduction of this pentacarbonyl with [[zinc]] and [[acetic acid]] gives [[pentacarbonylhydridorhenium]]:<ref name="Urb">{{cite book|author=Michael A. Urbancic|author2=John R. Shapley|chapter=Pentacarbonylhydridorhenium |title=Inorganic Syntheses|volume=28|pages=165–168|date=1990|doi =10.1002/9780470132593.ch43|isbn=978-0-470-13259-3}}</ref>
:Re(CO)<sub>5</sub>Br + Zn + HOAc → Re(CO)<sub>5</sub>H + ZnBr(OAc)

[[Methylrhenium trioxide]] ("MTO"), CH<sub>3</sub>ReO<sub>3</sub> is a volatile, colourless solid has been used as a [[catalyst]] in some laboratory experiments. It can be prepared by many routes, a typical method is the reaction of Re<sub>2</sub>O<sub>7</sub> and [[tetramethyltin]]:
:Re<sub>2</sub>O<sub>7</sub> + (CH<sub>3</sub>)<sub>4</sub>Sn → CH<sub>3</sub>ReO<sub>3</sub> + (CH<sub>3</sub>)<sub>3</sub>SnOReO<sub>3</sub>
Analogous alkyl and aryl derivatives are known. MTO catalyses for the oxidations with [[hydrogen peroxide]]. Terminal [[alkyne]]s yield the corresponding acid or ester, internal alkynes yield diketones, and [[alkene]]s give epoxides. MTO also catalyses the conversion of [[aldehyde]]s and [[diazoalkane]]s into an alkene.<ref>Hudson, A. (2002) “Methyltrioxorhenium” in ''Encyclopedia of Reagents for Organic Synthesis''. John Wiley & Sons: New York, {{ISBN|9780470842898}}, {{doi|10.1002/047084289X}}.</ref>