Germanium compounds

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Germanium compounds are

alkalis but dissolves slowly in hot concentrated sulfuric and nitric acids and reacts violently with molten alkalis to produce germanates ([GeO
3]2−
). Germanium occurs mostly in the oxidation state +4 although many +2 compounds are known.[1] Other oxidation states are rare: +3 is found in compounds such as Ge2Cl6, and +3 and +1 are found on the surface of oxides,[2] or negative oxidation states in germanides, such as −4 in Mg
2Ge. Germanium cluster anions (Zintl ions) such as Ge42−, Ge94−, Ge92−, [(Ge9)2]6− have been prepared by the extraction from alloys containing alkali metals and germanium in liquid ammonia in the presence of ethylenediamine or a cryptand.[1][3] The oxidation states of the element in these ions are not integers—similar to the ozonides
O3−.

Chalcogenides

Oxides

Two oxides of germanium are known: germanium dioxide (GeO
2, germania) and germanium monoxide, (GeO).[4] The dioxide, GeO2 can be obtained by roasting germanium disulfide (GeS
2) or by allowing elemental germanium to slowly oxidze in air,[5] and is a white powder that is only slightly soluble in water but reacts with alkalis to form germanates.[4] The monoxide, germanous oxide, can be obtained by the high temperature reaction of GeO2 with Ge metal.[4] The dioxide (and the related oxides and germanates) exhibits the unusual property of having a high refractive index for visible light, but transparency to infrared light.[6][7] Bismuth germanate, Bi4Ge3O12, (BGO) is used as a scintillator.[8]

Other chalcogenides

alkaline carbonates and sulfur, germanium compounds form salts known as thiogermanates.[10]

Hydrides

Skeletal chemical structure of a tetrahedral molecule with germanium atom in its center bonded to four hydrogen atoms. The Ge-H distance is 152.51 picometers.
Germane is similar to methane.

anion.[1] The germanium hydrohalides with one, two and three halogen atoms are colorless reactive liquids.[1]

Halides

Four tetra

halides are known. Under normal conditions GeI4 is a solid, GeF4 a gas and the others volatile liquids. For example, germanium tetrachloride, GeCl4, is obtained as a colorless fuming liquid boiling at 83.1 °C by heating the metal with chlorine.[4] All the tetrahalides are readily hydrolyzed to hydrated germanium dioxide.[4] GeCl4 is used in the production of organogermanium compounds.[1] All four dihalides are known and in contrast to the tetrahalides are polymeric solids.[1] Additionally Ge2Cl6 and some higher compounds of formula GenCl2n+2 are known.[4] The unusual compound Ge6Cl16 has been prepared that contains the Ge5Cl12 unit with a neopentane structure.[11]

Organogermanium compounds

Main article: Organogermanium chemistry
Skeletal chemical structures outlining an additive chemical reaction including an organogermanium compound.
Nucleophilic addition with an organogermanium compound.

The first

free radicals, germylenes (similar to carbenes), and germynes (similar to carbynes).[13][14] The organogermanium compound 2-carboxyethylgermasesquioxane was first reported in the 1970s, and for a while was used as a dietary supplement and thought to possibly have anti-tumor qualities.[15]

Using a ligand called Eind (1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl) germanium is able to form a double bond with oxygen (germanone). Germanium hydride and alkylgermanes are very flammable and even explosive when mixed with air.[16]

See also

References

  1. ^
    ISBN 978-0-08-037941-8
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  4. ^
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  5. doi:10.1016/S0169-4332(98)00251-7
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  6. doi:10.1111/j.1151-2916.2002.tb00594.x
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  8. S2CID 682173
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  9. doi:10.1021/cr60160a002
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  10. doi:10.1039/a703634e
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  11. PMID 11670739
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  12. doi:10.1002/prac.18870360119. Archived
    from the original on 2012-11-03. Retrieved 2008-08-20.
  13. S2CID 96576323
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  14. doi:10.1021/cr60224a004
    .
  15. PMID 9237323. Archived
    from the original on 2020-03-10. Retrieved 2019-06-30.
  16. ^ Broadwith, Phillip (25 March 2012). "Germanium-oxygen double bond takes centre stage". Chemistry World. Archived from the original on 2014-05-17. Retrieved 2014-05-15.
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