Germane

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Germanium tetrahydride
Structural formula of germane
Ball-and-stick model of the germane moleculeSpace-filling model of the germane molecule
Identifiers
CAS number7782-65-2 YesY
PubChem23984
ChemSpider22420 YesY
UN number2192
KEGGC15472 YesY
ChEBICHEBI:30443 YesY
RTECS numberLY4900000
Jmol-3D imagesImage 1
Properties
Molecular formulaGeH4
Molar mass76.62 g/mol1
AppearanceColorless gas
Density3.3 kg/m3 gas
Melting point−165 °C (108 K)
Boiling point−88 °C (185 K)
Solubility in waterlow
Structure
Molecular shapeTetrahedral
Dipole momentO D
Hazards
MSDSICSC 1244
EU IndexNot listed
Main hazardsToxic, flammable
NFPA 704
Related compounds
Related compoundsMethane
Silane
Stannane
Plumbane
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references
 
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For other meanings see germane.
Germanium tetrahydride
Structural formula of germane
Ball-and-stick model of the germane moleculeSpace-filling model of the germane molecule
Identifiers
CAS number7782-65-2 YesY
PubChem23984
ChemSpider22420 YesY
UN number2192
KEGGC15472 YesY
ChEBICHEBI:30443 YesY
RTECS numberLY4900000
Jmol-3D imagesImage 1
Properties
Molecular formulaGeH4
Molar mass76.62 g/mol1
AppearanceColorless gas
Density3.3 kg/m3 gas
Melting point−165 °C (108 K)
Boiling point−88 °C (185 K)
Solubility in waterlow
Structure
Molecular shapeTetrahedral
Dipole momentO D
Hazards
MSDSICSC 1244
EU IndexNot listed
Main hazardsToxic, flammable
NFPA 704
Related compounds
Related compoundsMethane
Silane
Stannane
Plumbane
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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.

Occurrence[edit]

Germane has been detected in the atmosphere of Jupiter.[1]

Synthesis[edit]

Germane is typically prepared by reduction of germanium compounds with hydride reagents such as sodium borohydride, potassium borohydride, lithium borohydride, lithium aluminium hydride, sodium aluminium hydride. The reaction is catalyzed by various acids and 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 these hydride reagents.[2][3] A typical synthesis involved the reaction of Na2GeO3 with sodium borohydride.[4]

Na2GeO3 + NaBH4 + H2O → GeH4 + 2 NaOH + NaBO2

Other methods for the synthesis of germane include electrochemical reduction and a plasma-based method.[5] 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 oxide or cadmium oxides. 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.

Reactions[edit]

Germane is weakly acidic. In liquid ammonia GeH4 is ionised forming NH4+ and GeH3.[6] 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.[6]

Use in semiconductor industry[edit]

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.[7] 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.[8]

Safety[edit]

Germane is a highly flammable, potentially pyrophoric,[9] and highly toxic gas. In 1970, the American Conference of Governmental Industrial Hygienists (ACGIH) published the latest changes and set the occupational exposure threshold limit value at 0.2 ppm for an 8 hour time weighted average.[10] The LC50 for rats at 1 hour of exposure is 622 ppm.[11] Inhalation exposure may result in malaise, headache, dizziness, fainting, dyspnea, nausea, vomiting, kidney injury, and hemolytic effects.[12][13][14]

The US Department of Transportation hazard class is 2.3 Poisonous Gas.[10]

References[edit]

  1. ^ Kunde, V.; Hanel, R.; Maguire, W.; Gautier, D.; Baluteau, J. P.; Marten, A.; Chedin, A.; Husson, N.; Scott, N. (1982). "The tropospheric gas composition of Jupiter's north equatorial belt (NH3, PH3, CH3D, GeH4, H2O) and the Jovian D/H isotopic ratio". Astrophysical Journal 263: 443–467. Bibcode:1982ApJ...263..443K. doi:10.1086/160516. 
  2. ^ W. L. Jolly "Preparation of the volatile hydrides of Groups IVA and VA by means of aqueous hydroborate" Journal of the American Chemical Society 1961, volume 83, pp. 335-7.
  3. ^ US Patent 4,668,502
  4. ^ Girolami, G. S.; Rauchfuss, T. B.; Angelici, R. J. (1999). Synthesis and Technique in Inorganic Chemistry. Mill Valley, CA: University Science Books. 
  5. ^ US Patent 7,087,102 (2006)
  6. ^ a b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419. 
  7. ^ Venkatasubramanian, R.; Pickett, R. T.; Timmons, M. L. (1989). "Epitaxy of germanium using germane in the presence of tetramethylgermanium". Journal of Applied Physics 66 (11): 5662–5664. Bibcode:1989JAP....66.5662V. doi:10.1063/1.343633. 
  8. ^ Woelk, E.; Shenai-Khatkhate, D. V.; DiCarlo, R. L. Jr., Amamchyan, A.; Power, M. B.; Lamare, B.; Beaudoin, G.; Sagnes, I. (2006). "Designing Novel Organogermanium MOVPE Precursors for High-purity Germanium Films". Journal of Crystal Growth 287 (2): 684–687. Bibcode:2006JCrGr.287..684W. doi:10.1016/j.jcrysgro.2005.10.094. 
  9. ^ Brauer, 1963, Vol.1, 715
  10. ^ a b Praxair MSDS accessed Sep. 2011
  11. ^ NIOSH Germane Registry of Toxic Effects of Chemical Substances (RTECS)accessed Sep. 2011
  12. ^ Gus'kova, E. I. (1974). "K toksikologii Gidrida Germaniia" [Toxicology of germanium hydride]. Gigiena Truda i Professionalnye Zabolevaniia (in Russian) 18 (2): 56–57. PMID 4839911. 
  13. ^ US EPA Germane
  14. ^ Paneth, F.; Joachimoglu, G. (1924). "Über die pharmakologischen Eigenschaften des Zinnwasserstoffs und Germaniumwasserstoffs" [About the pharmacological characteristics of tin hydride and germanium hydride]. Berichte der Deutschen Chemischen Gesellschaft (in German) 57 (10): 1925–1930. doi:10.1002/cber.19240571027. 

External links[edit]