Germanium(II) iodide
{{Chembox
|ImageFile=Kristallstruktur Cadmiumiodid.png
|Section3={{Chembox Structure
| SpaceGroup= P{{overline|3}}m1 (No. 164){{citation|author=Jean d’Ans, Ellen Lax, Roger Blachnik|date=1998|isbn=364258842-5|pages=472|publisher=Springer DE|title=Taschenbuch für Chemiker und Physiker|url=https://books.google.com/books?id=ssy59etLaksC&pg=PA472}}
}}
|Section1={{Chembox Identifiers
| CASNo=13573-08-5
| CASNo_Ref = {{cascite|correct|CAS}}
| EINECS= 236-998-1
| PubChem = 6327215
| ChemSpiderID = 4885744
| SMILES=I[Ge]I
}}
|Section2={{Chembox Properties
|Ge=1|I=2
| Density= 5.37 g·cm−3 (25 °C){{Sigma-Aldrich|Aldrich|383260|Name=Germanium(II) iodide, ≥99.9% trace metals basis|Abruf=2014-01-19}}
| BoilingPt= 550 °C (decomposes)
|Solubility=
}}
|Section8={{Chembox Related
| OtherCations=tin(II) iodide
lead(II) iodide
| OtherAnions=germanium(II) fluoride
germanium(II) chloride
germanium(II) bromide
| OtherCompounds=germanium(IV) iodide
}}
}}
Germanium(II) iodide is an iodide of germanium, with the chemical formula of GeI2.
Preparation
Germanium(II) iodide can be produced by reacting germanium(IV) iodide with hydriodic acid and hypophosphorous acid and water:Georg Brauer (Hrsg.), unter Mitarbeit von Marianne Baudler u. a.: Handbuch der Präparativen Anorganischen Chemie. 3., umgearbeitete Auflage. Band I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6, S. 727.
:{{chem2|GeI4 + H2O + H3PO2 -> GeI2 + H3PO3 + 2 HI}}
It can also be formed by the reaction of germanium monosulfide or germanium monoxide and hydrogen iodide.
:{{chem2|GeO + 2 HI -> GeI2 + H2O}}
:{{chem2|GeS + 2 HI -> GeI2 + H2S}}}
It can also be produced from the direct reaction of germanium and iodine at 200 – 400 °C:
:{{chem2|Ge + I2 -> GeI2}}
Germanium(II) iodide can also be formed from the decomposition of HGeI3, which can be prepared by reacting HGeCl3 with hydroiodic acid:{{citation|author=Wolfgang Kirmse|date=2013|isbn=978-032316145-9|pages=540|publisher=Elsevier|title=Carbene Chemistry 2e|url=https://books.google.com/books?id=T3dnOIFjwWwC&pg=PA540}}
:{{chem2|HGeCl3 + 3 HI -> HGeI3 + HCl}}
:{{chem2|HGeI3 -> GeI2 + HI}}
Properties
Germanium(II) iodide is a yellow crystal that slowly hydrolyzes into germanium(II) hydroxide in the presence of moisture. It is insoluble in hydrocarbons and slightly soluble in chloroform and carbon tetrachloride. It has a cadmium iodide structure with lattice parameters a = 413 pm and c = 679 pm. It disproportionates to germanium and germanium tetraiodide at 550 °C.{{Holleman&Wiberg|edition=101|page=959}}
Applications
Germanium(II) iodide can react with carbene to form stable compounds. It is also used in the electronics industry to produce germanium layers epitaxially through disproportionation reactions.{{citation|author=A.G. Milnes|date=1972|isbn=032314136-6|pages=104|publisher=Elsevier|title=Heterojunctions and Metal Semiconductor Junctions|url=https://books.google.com/books?id=Ox3JhIg40hcC&pg=PA104}}