Germanium dichloride is a chemical compound of germanium and chlorine with the formula GeCl2. It is a yellow solid. Germanium dichloride is an example of a compound featuring germanium in the +2 oxidation state.
Germanium dichloride is also formed from the decomposition of trichlorogermane, GeHCl3, at 70 °C. Trichlorogermane is generated when germanium reacts with hydrogen chloride.[1] This reaction involves dehydrohalogenation.
GeHCl3 → GeCl2 + HCl
Another route to germanium dichloride is the reduction of germanium tetrachloride with hydrogen at 800 °C.[1]
GeCl2 is hydrolysed to give yellow germanium(II) hydroxide, which on warming gives brown germanium monoxide:[1]
GeCl2 + 2 H2O ⇌ Ge(OH)2(s) + 2 HCl
Ge(OH)2 → GeO + H2O
Alkalizing a solution containing germanium(II) ions:
Ge2+ + 2 OH− → Ge(OH)2
Germanium oxides and hydroxides are amphoteric.
Solutions of GeCl2 in HCl are strongly reducing.[2] With chloride ion, ionic compounds containing the pyramidal GeCl−3 ion have been characterised, for example [3] With rubidium and caesium chloride compounds, e.g. RbGeCl3 are produced; these have distorted perovskite structures.[1]
Molecular GeCl2 is often called dichlorogermylene, highlighting its resemblance to a carbene. The structure of gas-phase molecular GeCl2 shows that it is a bent molecule, as predicted by VSEPR theory.[5] The dioxane complex, GeCl2·dioxane, has been used as a source of molecular GeCl2 for reaction syntheses, as has the in situ reaction of GeCl4 and Ge metal. GeCl2 is quite reactive and inserts into many types of chemical bonds.[6] Usually, germanium dichloride is generated from germanium dichloride dioxane.
^Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN0-12-352651-5
^Kociok-Köhn, G.; Winter, J. G.; Filippou, A. C. (1999). "Trimethylphosphonium trichlorogermanate(II)". Acta Crystallogr. C. 55 (3): 351–353. doi:10.1107/S010827019801169X.
