Germanium dichloride

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

Names
Preferred IUPAC name Germanium dichloride
Systematic IUPAC name Dichlorogermanylidene
Other names Dichlorogermylene Germanium(II) chloride Germanous chloride
Identifiers
CAS Number	10060-11-4
3D model (JSmol)	Interactive image
ChemSpider	4885679
ECHA InfoCard	100.030.162
EC Number	233-192-1
PubChem CID	6327122
UNII	SI7JKX4F22 Y
CompTox Dashboard (EPA)	DTXSID40143425
InChI InChI=1S/Cl2Ge/c1-3-2 Key: QHGIKMVOLGCZIP-UHFFFAOYSA-N
SMILES Cl[Ge]Cl
Properties
Chemical formula	GeCl2
Molar mass	143.546 g/mol
Appearance	white-pale yellow solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Solid germanium dichloride can be produced by comproportionation by passing germanium tetrachloride, GeCl₄, over germanium metal at 300 °C and reduced pressure (0.1 mmHg).^[1]

GeCl₄ + Ge → 2 GeCl₂

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]

GeCl₄ + H₂ → GeCl₂ + 2HCl

Reactions

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]

Germanium dichloride reacts with tetraethylammonium chloride to give the trichlorogermanate:^[4]

GeCl₂ + Et₄NCl → Et₄NGeCl₃

Dichlorogermylene

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.