Germanium(II) iodide

Germanium(II) iodide is an iodide of germanium, with the chemical formula of GeI₂.

Germanium(II) iodide

Identifiers
CAS Number	13573-08-5 Y
3D model (JSmol)	Interactive image
ChemSpider	4885744
ECHA InfoCard	100.033.620
EC Number	236-998-1
PubChem CID	6327215
CompTox Dashboard (EPA)	DTXSID50929131
SMILES I[Ge]I
Properties
Chemical formula	GeI2
Molar mass	326.439 g·mol−1
Appearance	yellow solid[1]
Density	5.37 g·cm−3 (25 °C)[2]
Melting point	428 °C[3]
Boiling point	550 °C (decomposes)[3]
Structure
Space group	P3m1 (No. 164)[4]
Related compounds
Other anions	germanium(II) fluoride germanium(II) chloride germanium(II) bromide
Other cations	tin(II) iodide lead(II) iodide
Related compounds	germanium(IV) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Germanium(II) iodide can be produced by reacting germanium(IV) iodide with hydriodic acid and hypophosphorous acid and water:^[1]

GeI₄ + H₂O + H₃PO₂ → GeI₂ + H₃PO₃ + 2 HI

It can also be formed by the reaction of germanium monosulfide or germanium monoxide and hydrogen iodide.^[1]

GeO + 2 HI → GeI₂ + H₂O

GeS + 2 HI → GeI₂ + H₂S}

It can also be produced from the direct reaction of germanium and iodine at 200 – 400 °C:^[1]

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:^[5]

HGeCl₃ + 3 HI → HGeI₃ + HCl

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.^[1] It disproportionates to germanium and germanium tetraiodide at 550 °C.^[6]

Applications

Germanium(II) iodide can react with carbene to form stable compounds.^[2] It is also used in the electronics industry to produce germanium layers epitaxially through disproportionation reactions.^[7]