Germanium compounds

Two oxides of germanium are known: germanium dioxide ({{chem|GeO|2}}, germania) and germanium monoxide, ({{chem|GeO}}).{{cite book|last = Holleman|first = A. F.|author2=Wiberg, E.|author3=Wiberg, N.|title=Lehrbuch der Anorganischen Chemie|edition=102nd|publisher=de Gruyter|date=2007|isbn=978-3-11-017770-1|oclc = 145623740}} The dioxide, GeO₂ can be obtained by roasting germanium disulfide ({{chem|GeS|2}}) or by allowing elemental germanium to slowly oxidze in air,{{cite journal|doi=10.1016/S0169-4332(98)00251-7|title=KRXPS study of the oxidation of Ge(001) surface|date=1998|author=Tabet, N|journal=Applied Surface Science|volume=134|issue=1–4|pages=275–282|bibcode = 1998ApSS..134..275T|last2=Salim|first2=Mushtaq A. }} and is a white powder that is only slightly soluble in water but reacts with alkalis to form germanates. The monoxide, germanous oxide, can be obtained by the high temperature reaction of GeO₂ with Ge metal. 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.{{cite journal|doi = 10.1111/j.1151-2916.2002.tb00594.x|title = Infrared Transparent Germanate Glass-Ceramics|first = Shyam S.|last = Bayya|author2=Sanghera, Jasbinder S.|author3=Aggarwal, Ishwar D.|author4=Wojcik, Joshua A.|journal = Journal of the American Ceramic Society|volume = 85|issue = 12|pages= 3114–3116|date = 2002}}{{cite journal|doi = 10.1007/BF00614256|title = Infrared reflectance and transmission spectra of germanium dioxide and its hydrolysis products|date = 1975 |last1 = Drugoveiko|first1 = O. P.|journal = Journal of Applied Spectroscopy|volume = 22|issue = 2|pages = 191–193|last2 = Evstrop'ev|first2 = K. K.|last3 = Kondrat'eva|first3 = B. S.|last4 = Petrov|first4 = Yu. A.|last5 = Shevyakov|first5 = A. M.|bibcode=1975JApSp..22..191D|s2cid = 97581394}} Bismuth germanate, Bi₄Ge₃O₁₂, (BGO) is used as a scintillator.{{cite journal|title = A Bismuth Germanate-Avalanche Photodiode Module Designed for Use in High Resolution Positron Emission Tomography|last = Lightstone|first = A. W.|author2=McIntyre, R. J.|author3=Lecomte, R.|author4=Schmitt, D.|journal = IEEE Transactions on Nuclear Science| date = 1986|volume =33|issue= 1|pages = 456–459|doi =10.1109/TNS.1986.4337142|bibcode = 1986ITNS...33..456L |s2cid = 682173}}

Binary compounds with other chalcogens are also known, such as the disulfide ({{chem|GeS|2}}), diselenide ({{chem|GeSe|2}}), and the monosulfide (GeS), selenide (GeSe), and telluride (GeTe). GeS₂ forms as a white precipitate when hydrogen sulfide is passed through strongly acid solutions containing Ge(IV). The disulfide is appreciably soluble in water and in solutions of caustic alkalis or alkaline sulfides. Nevertheless, it is not soluble in acidic water, which allowed Winkler to discover the element.{{cite journal|first =Otto H.|last = Johnson|title = Germanium and its Inorganic Compounds|journal = Chem. Rev.|date = 1952|volume= 51|issue =3| pages=431–469|doi = 10.1021/cr60160a002}} By heating the disulfide in a current of hydrogen, the monosulfide (GeS) is formed, which sublimes in thin plates of a dark color and metallic luster, and is soluble in solutions of the caustic alkalis. Upon melting with alkaline carbonates and sulfur, germanium compounds form salts known as thiogermanates.{{cite journal|doi=10.1039/a703634e|title=First synthesis of mesostructured thiogermanates|date=1997|last1 = Fröba|first1 = Michael |journal=Chemical Communications|issue=18|pages=1729–1730|last2=Oberender|first2=Nadine}}

File:Germane-2D-dimensions.svg.|alt=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 (GeH₄) is a compound similar in structure to methane. Polygermanes—compounds that are similar to alkanes—with formula Ge_nH_2n+2 containing up to five germanium atoms are known. The germanes are less volatile and less reactive than their corresponding silicon analogues. GeH₄ reacts with alkali metals in liquid ammonia to form white crystalline MGeH₃ which contain the GeH₃⁻ anion. The germanium hydrohalides with one, two and three halogen atoms are colorless reactive liquids.

Four tetrahalides 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. All the tetrahalides are readily hydrolyzed to hydrated germanium dioxide. GeCl₄ is used in the production of organogermanium compounds. All four dihalides are known and in contrast to the tetrahalides are polymeric solids. Additionally Ge₂Cl₆ and some higher compounds of formula Ge_nCl_2n+2 are known. The unusual compound Ge₆Cl₁₆ has been prepared that contains the Ge₅Cl₁₂ unit with a neopentane structure.{{cite journal|title = The Crystal Structure and Raman Spectrum of Ge₅Cl₁₂·GeCl₄ and the Vibrational Spectrum of Ge₂Cl₆| last = Beattie|first = I.R.|author2=Jones, P.J.|author3=Reid, G.|author4=Webster, M.|journal = Inorg. Chem.|volume = 37|issue =23|pages = 6032–6034|date = 1998|doi =10.1021/ic9807341|pmid = 11670739}}

{{Main article|Organogermanium chemistry}}

File:NucleophilicAdditionWithOrganogermanium.png addition with an organogermanium compound.|alt=Skeletal chemical structures outlining an additive chemical reaction including an organogermanium compound.]]

The first organogermanium compound was synthesized by Winkler in 1887; the reaction of germanium tetrachloride with diethylzinc yielded tetraethylgermane ({{chem|Ge(C|2|H|5|)|4}}).{{cite journal |first = Clemens |last = Winkler |author-link = Clemens Winkler |journal = J. Prak. Chemie |volume = 36 |issue = 1 |date = 1887 |pages = 177–209 |title = Mittheilungen über des Germanium. Zweite Abhandlung |doi = 10.1002/prac.18870360119 |url = http://gallica.bnf.fr/ark:/12148/bpt6k90799n/f183.table |access-date = 2008-08-20 |language = de |archive-date = 2012-11-03 |archive-url = https://web.archive.org/web/20121103012004/http://gallica.bnf.fr/ark:/12148/bpt6k90799n/f183.table |url-status = live }} Organogermanes of the type R₄Ge (where R is an alkyl) such as tetramethylgermane ({{chem|Ge(CH|3|)|4}}) and tetraethylgermane are accessed through the cheapest available germanium precursor germanium tetrachloride and alkyl nucleophiles. Organic germanium hydrides such as isobutylgermane ({{chem|(CH|3|)|2|CHCH|2|GeH|3}}) were found to be less hazardous and may be used as a liquid substitute for toxic germane gas in semiconductor applications. Many germanium reactive intermediates are known: germyl free radicals, germylenes (similar to carbenes), and germynes (similar to carbynes).{{cite journal|title = Reactive intermediates in organogermanium chemistry|first = Jacques|last = Satge|journal = Pure Appl. Chem.|volume = 56|issue = 1|pages = 137–150|date =1984|doi = 10.1351/pac198456010137|s2cid = 96576323|doi-access = free}}{{cite journal|title = Organogermanium Chemistry| first = Denis|last = Quane|author2=Bottei, Rudolph S.|journal = Chemical Reviews|volume = 63|issue = 4|pages = 403–442|date =1963|doi = 10.1021/cr60224a004}} 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.{{cite journal|last = Tao|first = S. H.|author2 = Bolger, P. M.|date = June 1997|title = Hazard Assessment of Germanium Supplements|journal = Regulatory Toxicology and Pharmacology|volume = 25|issue = 3|pages = 211–219|doi = 10.1006/rtph.1997.1098|pmid = 9237323|url = https://zenodo.org/record/1229957|access-date = 2019-06-30|archive-date = 2020-03-10|archive-url = https://web.archive.org/web/20200310041729/https://zenodo.org/record/1229957|url-status = live}}

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.{{cite news|last=Broadwith|first=Phillip|title=Germanium-oxygen double bond takes centre stage|url=http://www.rsc.org/chemistryworld/News/2012/March/germanone-germanium-oxygen-double-bond-created.asp|access-date=2014-05-15|newspaper=Chemistry World|date=25 March 2012|archive-date=2014-05-17|archive-url=https://web.archive.org/web/20140517121351/http://www.rsc.org/chemistryworld/News/2012/March/germanone-germanium-oxygen-double-bond-created.asp|url-status=live}}

• :Category:Germanium compounds
• Silicon compounds
• Tin compounds
• Gallium compounds
• Arsenic compounds

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{{Germanium compounds}}

Compounds

Category:Germanium compounds

Category:Chemical compounds by element