Organogermanium compound

The main reason why the organogermanium is of limited synthetic value are the costs of germanium compounds. On the other hand germanium is advocated as a non-toxic alternative to many toxic organotin reagents and compounds like tetramethylgermanium and tetraethylgermanium are used in the microelectronics industry as precursors for germanium oxide chemical vapor deposition.

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Organogermanes

Organogermanes of the type R₄Ge with alkyl (R) groups are accessed through the cheapest available germanium precursor germanium tetrachloride and alkyl nucleophiles. The following trends are observed going down the carbon group: The nucleophilicty increases Sihyperconjugation effect known as the beta-silicon effect Siionic and the Sn-C bond is mainly radical, bonds with germanium are in between.

Just as with silicon the nucleophilicity of allyl germanes is high due to the intrinsic polarization of the bond (difference in electronegativity 2.55 − 2.01 = 0.54) and the combined stabilizing effect on the α-carbonion by the allyl group and the germanium atom. The germanium pendant of the Sakurai reaction was discovered in 1986:

The carbonyl group in this reaction is activated with boron trifluoride.

Germanium hydrides

Isobutylgermane (IBGe) (Me₂CHCH₂)GeH₃ is the organogermanium hydride that is a high vapor pressure liquid germanium source for MOVPE. Isobutylgermane is currently investigated as safer and less hazardous alternative to toxic germane gas in microelectonic applications.

Tris(trimethylsilyl)germanium hydride (Me₃Si)₃GeH has been investigated as a non-toxic alternative to many tin hydrides such as tributyltinhydride.

Other germanium compounds

Many germanium reactive intermediates are known: germylenes (carbene pendants), germyl free radicals, germynes (carbyne pendants).^[2]

As with silicon and contrasting with carbon, compounds containing Ge-C and Ge-Ge double bonds are unstable but known for instance the benzene pendant germanabenzene.

See also

• Compounds of carbon with other elements in the periodic table:

References

1. ^ Main Group Metals in Organic Synthesis, Hisashi Yamamoto (Editor), Koichiro Oshima (Editor) ISBN 3-527-30508-4 2004
2. ^ Reactive intermediates in organogermanium chemistry Jacques Satge Pure & Appl. Chem., Vol.56, No.1, pp.137—150, 1984.