| Revision as of 12:27, 15 February 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 473912080 of page Gallium(III)_bromide for the Chem/Drugbox validation project (updated: 'CASNo'). |
Latest revision as of 02:13, 20 October 2024 edit Eyesnore (talk | contribs)Extended confirmed users, New page reviewers, Pending changes reviewers, Rollbackers38,534 edits →ReferencesTag: 2017 wikitext editor |
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{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}} |
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| verifiedrevid = 400098825 |
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| Name = Gallium(III) bromide |
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| verifiedrevid = 476994197 |
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| ImageFile = Gallium-bromide-3D-balls.png |
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| Name = Gallium(III) bromide (dimer) |
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| ImageName = Gallium(III) bromide |
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| ImageFile = Gallium-bromide-3D-balls.png |
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| ImageFile1 = Gallium-bromide-3D-vdW.png |
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| OtherNames = gallium tribromide |
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| ImageName = Gallium(III) bromide (dimer) |
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| Section1 = {{Chembox Identifiers |
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| OtherNames = gallium tribromide |
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| Section1 = {{Chembox Identifiers |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 75315 |
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| ChemSpiderID = 75315 |
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| EC_number = 236-609-5 |
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| InChI = 1/3BrH.Ga/h3*1H;/q;;;+3/p-3 |
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| InChI = 1/3BrH.Ga/h3*1H;/q;;;+3/p-3 |
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| InChIKey = SRVXDMYFQIODQI-DFZHHIFOAJ |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = SRVXDMYFQIODQI-UHFFFAOYSA-K |
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| StdInChIKey = SRVXDMYFQIODQI-UHFFFAOYSA-K |
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| CASNo_Ref = {{cascite|correct|??}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo = <!-- blanked - oldvalue: 13450-88-9 --> |
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| CASNo = 13450-88-9 |
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| PubChem = 83477 |
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| PubChem = 83477 |
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| Section2 = {{Chembox Properties |
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| Section2 = {{Chembox Properties |
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| Formula = GaBr<sub>3</sub> |
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| Formula = GaBr<sub>3</sub> |
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| MolarMass = 309.435 g/mol |
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| MolarMass = 309.435 g/mol |
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| Appearance = white powder |
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| Appearance = white powder |
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| Density = 3.69 g/cm<sup>3</sup> |
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| Density = 3.69 g/cm<sup>3</sup> |
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| Solubility = soluble |
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| Solubility = soluble |
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| MeltingPt = 121.5°C |
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| MeltingPtC = 121.5 |
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| BoilingPt = 278.8°C |
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| BoilingPtC = 278.8 |
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'''Gallium(III) bromide''' (]]) is a ], and one of four ] trihalides. |
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==Introduction== |
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Gallium(III) bromide is, at room temperature and atmospheric pressure, a white, crystalline powder which reacts favorably and exothermically with water.<ref>{{cite web |url=http://www.sigmaaldrich.com/catalog/product/aldrich/450863?lang=en®ion=US |title=Gallium(III) bromide |website=Sigma Aldrich Catalogue |publisher=Sigma Aldrich Company }}</ref> Solid gallium tribromide is stable at room temperature and can be found primarily in its dimeric form.<ref name=":0">{{cite book |title=Encyclopedia of Inorganic Chemistry |last=King |first=Bruce R. |publisher=Wiley |year=1994 |isbn=978-0-471-93620-6<!--|location=Chichester--> |location=New York |pages=1265–1267}}</ref> GaBr<sub>3</sub> can form an intermediate halide, Ga<sub>2</sub>Br<sub>7;</sub> however, this is not as common as with GaCl<sub>3</sub>. It is a member of the gallium trihalide group and is similar to GaCl<sub>3</sub>, and GaI<sub>3</sub>, but not GaF<sub>3</sub>, in its preparation and uses.<ref name=":0" /> GaBr<sub>3</sub> is a milder Lewis acid than AlBr<sub>3</sub>, and has more versatile chemistry due to the comparative ease of reducing gallium, but is more reactive than GaCl<sub>3</sub>.<ref>{{cite journal |last1=Kiyokawa |first1=Kensuke |last2=Yasuda |first2=Makoto |last3=Baba |first3=Akio |date=2010-04-02 |title=Cyclopropylmethylation of Benzylic and Allylic Chlorides with Cyclopropylmethylstannane Catalyzed by Gallium or Indium Halide |journal=Organic Letters |volume=12 |issue=7 |pages=1520–1523 |doi=10.1021/ol100240b |pmid=20218636 |issn=1523-7060}}</ref> |
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GaBr<sub>3</sub> is similar spectroscopically to aluminum, indium, and thallium trihalides excluding trifluorides.<ref>{{cite book|last1=Downs|first1=A.J.|title=Chemistry of Aluminium Gallium Indium and Thallium|date=199|publisher=Springer Science & Business Media|page=133}}</ref> |
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==Preparation== |
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One method of preparing GaBr<sub>3</sub> is to heat elemental gallium in the presence of bromine liquid under vacuum.<ref name=":2">{{Cite journal|last1=Johnson|first1=W. C.|last2=Parsons|first2=J. B.|date=1929-01-01|title=The Preparation of Gallium Tribromide and Gallium Triiodide|journal=The Journal of Physical Chemistry|volume=34|issue=6|pages=1210–1214|doi=10.1021/j150312a007|issn=0092-7325}}</ref> Following the highly exothermic reaction, the mixture is allowed to rest and then subjected to various purifying steps. This method from the turn of the twentieth century remains a useful way of preparing GaBr<sub>3.</sub> Historically, gallium was obtained by electrolysis of its hydroxide in solution of potassium hydroxide, however today it is obtained as a byproduct of aluminium and zinc production. |
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GaBr<sub>3</sub> can be synthesized by exposing gallium to bromine in an environment free of water, oxygen and grease.<ref name=":2" /><ref name=":1">{{cite book|title=Chemistry of Aluminium Gallium Indium and Thallium|date=199|publisher=Springer Science & Business Media|page=133|last1=Downs|first1=A.J.}}</ref> The result is a gas which must be crystallized in order to form bromide purchased by laboratories. Below is the equation: |
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:{{chem2 | 2 Ga(s) + 3 Br2(l) -> 2 GaBr3(g) }} |
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== Structure == |
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The GaBr<sub>3</sub> monomer has trigonal planar geometry, but when it forms the dimer Ga<sub>2</sub>Br<sub>6</sub> the geometry around the gallium center distorts to become roughly tetrahedral. As a solid, GaBr<sub>3</sub> forms a monoclinic crystalline structure with a unit cell volume of 524.16 Å<sup>3</sup>. Additional specifications for this unit cell are as follows: a = 8.87 Å, b = 5.64 Å, c =11.01 Å, α = 90˚, β = 107.81˚, γ = 90˚.<ref>{{Cite journal|author1=Troyanov, S.I. |author2=Krahl, T. |author3=Kemnitz, E. |title=Crystal structures of Ga''X''<sub>3</sub> (''X'' = Cl, Br, I) and AlI<sub>3</sub> |journal=Zeitschrift für Kristallographie |volume=219 |issue=2 |year=2004|pages=88–92|doi=10.1524/zkri.219.2.88.26320|bibcode=2004ZK....219...88T |s2cid=101603507 }}</ref> |
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==Complexes== |
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Gallium is the lightest group 13 metal with a filled d-shell, and has an electronic configuration of ( 3d<sup>10</sup> 4s<sup>2</sup> 4p<sup>1</sup>) below the valence electrons that could take part in d-π bonding with ligands. The somewhat high oxidation state of Ga in Ga(III)Br<sub>3</sub>, low electronegativity, and high polarizability allow GaBr<sub>3</sub> to behave as a "soft acid" in terms of the ]. The Lewis acidity of all the gallium trihalides, GaBr<sub>3</sub> included, has been extensively studied thermodynamically, and the basicity of GaBr<sub>3</sub> has been established with a number of donors.<ref name=":0" /> |
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GaBr<sub>3</sub> is capable of accepting an additional Br<sup>−</sup> ion or unevenly splitting its dimer to form <sup>−</sup>, a tetrahedral ion of which crystalline salts can be obtained.<ref name=":0" /><ref name=":3">{{Cite journal|last1=El-Hellani|first1=Ahmad|last2=Monot|first2=Julien|last3=Guillot|first3=Régis|last4=Bour|first4=Christophe|last5=Gandon|first5=Vincent|date=2013-01-07|title=Molecular versus Ionic Structures in Adducts of GaX3 with Monodentate Carbon-Based Ligands|journal=Inorganic Chemistry|volume=52|issue=1|pages=506–514|doi=10.1021/ic302440g|pmid=23256783|issn=0020-1669}}</ref> This ionic complex is further capable of binding to . The Br<sup>−</sup> ion can be just as easily substituted with a neutral ligand. Typically these neutral ligands, with form GaBr<sub>3</sub> L and sometimes GaBr<sub>3</sub>L<sub>2</sub>, will form a tetrahedral bipyramidal geometric structure with the Br in an equatorial position due to their large effective nuclear charge.<ref name=":0" /> Additionally, GaBr<sub>3</sub> can be used as a catalyst in certain oxidative addition reactions. |
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==Uses== |
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GaBr<sub>3</sub> is used as a catalyst in organic synthesis, with similar mechanism to GaCl<sub>3.</sub> However, due to its greater reactivity, it is sometimes disfavored because of the greater versatility of GaCl<sub>3</sub>.<ref name=":0" /> GaBr<sub>3</sub> as well as other gallium trihalides and group 13 metal trihalides can be used as catalysts in the oxidative addition of organic compounds. It has been verified that the GaBr<sub>3</sub> dimer cleaves unevenly into <sup>−</sup> and <sup>+</sup>.<ref name=":3" /> The entire mechanism is uncertain partly because intermediate states are not always stable enough for study, and partially because GaBr<sub>3</sub> is studied less frequently than GaCl<sub>3</sub>. Ga(III) itself is a useful Lewis acid for organic reactions because its full d-electron shell makes it able to accept variable numbers of ligands, but will readily give up ligands if conditions prove favorable. |
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==See also== |
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* ] |
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* ] |
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==References== |
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<references/> |
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{{Gallium compounds}} |
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{{bromides}} |
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] |
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