Germanium(II) iodide is an iodide of germanium, with the chemical formula of GeI2.
Germanium(II) iodide can be produced by reacting germanium(IV) iodide with hydriodic acid and hypophosphorous acid and water:[1]
It can also be formed by the reaction of germanium monosulfide or germanium monoxide and hydrogen iodide.
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It can also be produced from the direct reaction of germanium and iodine at 200 – 400 °C:
Germanium(II) iodide can also be formed from the decomposition of HGeI3, which can be prepared by reacting HGeCl3 with hydroiodic acid:
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.
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.