| Germanium tetrahydride | |
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| IUPAC name |
Germane
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| Other names | Germanium tetrahydride Germanomethane Monogermane |
| Identifiers | |
| CAS number | 7782-65-2  |
| UN number | 2192 |
| RTECS number | LY4900000 |
| Properties | |
| Molecular formula | GeH4 |
| Molar mass | 76.62 g/mol1 |
| Appearance | Colorless gas |
| Density | 3.3 kg/m3 gas |
| Melting point |
−165 °C (108 K) |
| Boiling point |
−88 °C (195 K) |
| Solubility in water | low |
| Structure | |
| Molecular shape | Tetrahedral |
| Dipole moment | O D |
| Hazards | |
| MSDS | ICSC 1244 |
| EU Index | Not listed |
| Main hazards | Toxic, flammable |
| NFPA 704 |
4
4
3
|
| Related compounds | |
| Related compounds | Methane Silane Stannane Plumbane |
 (what is this?) (verify)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Germane is the chemical compound with the formula GeH4, and the germanium analogue of methane. It is the simplest germanium hydride and one of the most useful compounds of germanium. Like the related compounds silane and methane, germane is tetrahedral. It burns in air to produce GeO2 and water.
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Germane has been detected in the atmosphere of Jupiter.[1]
Many methods are known for the industrial manufacture of germane.[2] These processes can be categorized as (a) chemical reduction method, (b) an electrochemical reduction method, and (c) a plasma based method.
The chemical reduction method involves reacting a germanium-containing compound such as elemental germanium, germanium tetrachloride, or germanium dioxide with a reducing agent such as sodium borohydride, potassium borohydride, lithium borohydride, lithium aluminium hydride, sodium aluminium hydride, lithium hydride, sodium hydride, or magnesium hydride. The reaction can be carried out in either aqueous or in an organic solvent. On laboratory scale, germane can be prepared by the reaction of Ge(IV) compounds with hydride reagents. A typical synthesis involved the reaction of Na2GeO3 with sodium borohydride.[3]
The electrochemical reduction method involves applying voltage to a germanium metal cathode immersed in an aqueous electrolyte solution and an anode counter-electrode composed of a metal such as molybdenum or cadmium. In this method, germane and hydrogen gases evolve from the cathode while the anode reacts to form solid molybdenum or cadmium oxides.
Lastly, the plasma synthesis method involves bombarding germanium metal with hydrogen atoms (H) that are generated using a high frequency plasma source to produce germane and digermane.
US Patent 4,668,502 discloses a process for manufacture of germane gas using germanium dioxide and sodium borohydride.
In liquid ammonia GeH4 is ionised forming NH4+ and GeH3−. [4] With alkali metals in liquid ammonia GeH4 reacts to give white crystalline MGeH3 compounds. The potassium and rubidium compounds have the sodium chloride structure implying a free rotation of the GeH3− anion, the caesium compound, CsGeH3 in contrast has the distorted sodium chloride structure of TlI.[4]
The gas decomposes near 600K to germanium and hydrogen. Because of its thermal lability, germane is used in the semiconductor industry for the epitaxial growth of germanium by MOVPE or chemical beam epitaxy.[5] Organogermanium precursors (e.g. isobutylgermane, alkylgermanium trichlorides, and dimethylaminogermanium trichloride) have been examined as less hazardous liquid alternatives to germane for deposition of Ge-containing films by MOVPE.[6]
Germane is flammable, potentially pyrophoric, and toxic.
Germane m. (genitive Germane, plural Germanen)
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