 | |||
| |||
| Names | |||
|---|---|---|---|
| IUPAC name Germane | |||
| Other names Germanium tetrahydride Germanomethane Monogermane Germanium(IV) hydride | |||
| Identifiers | |||
3D model (JSmol) | |||
| ChEBI | |||
| ChemSpider |
| ||
| ECHA InfoCard | 100.029.055 | ||
| EC Number |
| ||
| 587 | |||
| KEGG |
| ||
| RTECS number |
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| UNII | |||
| UN number | 2192 | ||
| |||
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| Properties | |||
| GeH4 | |||
| Molar mass | 76.62 g/mol | ||
| Appearance | Colorless gas | ||
| Odor | Pungent[1] | ||
| Density | 3.3 kg/m3 | ||
| Melting point | −165 °C (−265 °F; 108 K) | ||
| Boiling point | −88 °C (−126 °F; 185 K) | ||
| Low | |||
| Vapor pressure | >1 atm[1] | ||
| Viscosity | 17.21 μPa·s (theoretical estimate)[2] | ||
| Structure | |||
| Tetrahedral | |||
| 0 D | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards | Toxic, flammable, may ignite spontaneously in air | ||
| GHS labelling: | |||
   | |||
| Danger | |||
| H220,H302,H330 | |||
| P210,P260,P264,P270,P271,P284,P301+P312,P304+P340,P310,P320,P330,P377,P381,P403,P403+P233,P405,P410+P403,P501 | |||
| NFPA 704 (fire diamond) | |||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | None[1] | ||
REL (Recommended) | TWA 0.2 ppm (0.6 mg/m3)[1] | ||
IDLH (Immediate danger) | N.D.[1] | ||
| Safety data sheet (SDS) | ICSC 1244 | ||
| Related compounds | |||
Related compounds | Methane Silane Stannane Plumbane Germyl | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Germane is thechemical compound with the formulaGeH4, and thegermaniumanalogue ofmethane. It is the simplest germanium hydride and one of the most useful compounds of germanium. Like the related compoundssilane and methane, germane istetrahedral. It burns in air to produceGeO2 andwater. Germane is agroup 14 hydride.
Germane has been detected in the atmosphere ofJupiter.[3]
Germane is typically prepared by reduction of germanium oxides, notablygermanates, with hydride reagents such assodium borohydride,potassium borohydride,lithium borohydride,lithium aluminium hydride,sodium aluminium hydride. The reaction with borohydrides is catalyzed by various acids and can be carried out in either aqueous or organicsolvent. On laboratory scale, germane can be prepared by the reaction of Ge(IV) compounds with thesehydride reagents.[4][5] A typical synthesis involved the reaction of sodium germanate withpotassium borohydride.[6]
Other methods for the synthesis of germane includeelectrochemical reduction and aplasma-based method.[7] The electrochemical reduction method involves applyingvoltage to a germanium metalcathode immersed in an aqueouselectrolyte solution and ananode counter-electrode composed of a metal such asmolybdenum orcadmium. In this method, germane andhydrogen gases evolve from the cathode while the anode reacts to form solidmolybdenum oxide orcadmium oxides. The plasma synthesis method involves bombarding germanium metal with hydrogen atoms (H) that are generated using a highfrequency plasma source to produce germane anddigermane.
Germane is weaklyacidic. In liquid ammonia GeH4 is ionised forming NH4+ andGeH3−.[8] With alkali metals in liquid ammonia GeH4 reacts to give white crystalline MGeH3 compounds. The potassium (potassium germyl or potassium trihydrogen germanide KGeH3) and rubidium compounds (rubidium germyl or rubidium trihydrogen germanide RbGeH3) have thesodium chloride structure implying a free rotation of the trihydrogen germanide anion GeH3−, the caesium compound, caesium germyl or caesium trihydrogen germanide CsGeH3 in contrast has the distorted sodium chloride structure ofTlI.[8]
The gas decomposes near 600K (327°C; 620°F) to germanium and hydrogen. Because of its thermallability, germane is used in thesemiconductor industry for theepitaxial growth of germanium byMOVPE orchemical beam epitaxy.[9] 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.[10]
Germane is a highlyflammable, potentiallypyrophoric,[11] and a highly toxic gas. In 1970, theAmerican Conference of Governmental Industrial Hygienists (ACGIH) published the latest changes and set the occupational exposure threshold limit value at 0.2ppm for an 8-hour time weighted average.[12]TheLC50 for rats at 1 hour of exposure is 622 ppm.[13] Inhalation or exposure may result in malaise, headache, dizziness, fainting, dyspnea, nausea, vomiting, kidney injury, and hemolytic effects.[14][15][16]
TheUS Department of Transportationhazard class is 2.3 Poisonous Gas.[12]
