Tetramethylgermane
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Organogermanium compounds are organometallic compounds containing a
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
to
germanium Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors s ...
or
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
to germanium chemical bond. Organogermanium chemistry is the corresponding chemical science. Germanium shares group 14 in the periodic table with
silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...
,
tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
and
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
, and not surprisingly the chemistry of organogermanium is in between that of
organosilicon compounds Organosilicon compounds are organometallic compounds containing carbon–silicon bonds. Organosilicon chemistry is the corresponding science of their preparation and properties. Most organosilicon compounds are similar to the ordinary organic co ...
and
organotin compound Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry. The first organotin compound was diethyltin diiodide (), discovered by ...
s. One reason that limited
synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic o ...
value of organogermanium compound is costs of germanium compounds. On the other hand, germanium is advocated as a non-toxic alternative to many toxic organotin reagents. Compounds like tetramethylgermanium and
tetraethylgermanium Tetraethylgermanium (common name tetraethyl germanium), abbreviated TEG, is an organogermanium compound with the formula ( CH3CH2)4 Ge. Tetraethylgermanium is an important chemical compound used in vapour deposition of germanium which is in a tetra ...
are used in the microelectronics industry as precursors for germanium dioxide
chemical vapor deposition Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (substra ...
. The first organogermanium compound, tetraethylgermane, was synthesised by Winkler in 1887, by the reaction of germanium tetrachloride with diethylzinc. The organogermanium compound ''bis (2-Carboxyethylgermanium)sesquioxide'' was first reported in 1966.


Organogermanes

Organogermanes of the type R4Ge with
alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloalk ...
(R) groups are accessed through the cheapest available germanium precursor
germanium tetrachloride Germanium tetrachloride is a colourless, fuming liquid with a peculiar, acidic odour. It is used as an intermediate in the production of purified germanium metal. In recent years, GeCl4 usage has increased substantially due to its use as a reagent ...
and alkyl nucleophiles. The following trends are observed going down the carbon group: The nucleophilicity increases Sihyperconjugation In organic chemistry, hyperconjugation (σ-conjugation or no-bond resonance) refers to the delocalization of electrons with the participation of bonds of primarily σ-character. Usually, hyperconjugation involves the interaction of the electron ...
effect known as the beta-silicon effect Sielectronegativity 2.55 − 2.01 = 0.54) and the combined stabilizing effect on the α-carbonion by the
allyl In organic chemistry, an allyl group is a substituent with the structural formula , where R is the rest of the molecule. It consists of a methylene bridge () attached to a vinyl group (). The name is derived from the scientific name for garlic, ...
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 Boron trifluoride is the inorganic compound with the formula BF3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds. Structure and bondin ...
.


Hydrides

Isobutylgermane Isobutylgermane (IBGe, Chemical formula: (CH3)2CHCH2GeH3, is an organogermanium compound. It is a colourless, volatile liquid that is used in MOVPE (Metalorganic Vapor Phase Epitaxy) as an alternative to germane. IBGe is used in the deposition o ...
(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 Germane is the chemical compound with the formula Ge H4, 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 te ...
gas in microelectronic applications. Tris(trimethylsilyl)germanium hydride (Me3Si)3GeH has been investigated as a non-toxic alternative to many tin hydrides such as
tributyltin Tributyltin (TBT) is an umbrella term for a class of organotin compounds which contain the (C4H9)3 Sn group, with a prominent example being tributyltin oxide. For 40 years TBT was used as a biocide in anti-fouling paint, commonly known as botto ...
hydride.


Other compounds

Triphenylgermanol (Ph3GeOH) is known, existing as colorless solid. Like the isostructural silanol, it engages in hydrogen bonding in the solid-state. Many germanium
reactive intermediate In chemistry, a reactive intermediate or an intermediate is a short-lived, high-energy, highly reactive molecule. When generated in a chemical reaction, it will quickly convert into a more stable molecule. Only in exceptional cases can these comp ...
s are known: germylenes (
carbene In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is or where the R represents substituents or hydrogen atoms. The term "carbene" ma ...
pendants), germyl free radicals, germynes (
carbyne In organic chemistry, a carbyne is a general term for any compound whose structure consists of an electrically neutral carbon atom connected by a single covalent bond and has three non-bonded electrons. The carbon atom has either one or three ...
pendants). Digermynnes only exist for extremely bulky substituents. Unlike
alkyne \ce \ce Acetylene \ce \ce \ce Propyne \ce \ce \ce \ce 1-Butyne In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and n ...
s, the C-Ge-Ge-C core of these Digermynnes is nonlinear, although they are planar. The Ge-Ge distance is 2.22 Å, and the Ge-Ge-C angles are 131°. Such compounds are prepared by the reduction of bulky arylgermanium(II) halides.Philip P. Power "Bonding and Reactivity of Heavier Group 14 Element Alkyne Analogues" Organometallics 2007, volume 26, pp 4362–4372. As with silicon and contrasting with carbon, compounds containing Ge=C (germenes) and Ge=Ge (digermylenes) double bonds are rare. One example is the bulky derivatives of
germabenzene Germabenzene (C5H6Ge) is the parent representative of a group of chemical compounds containing in their molecular structure a benzene ring with a carbon atom replaced by a germanium atom. Germabenzene itself has been studied theoretically, and syn ...
, an analogue of benzene.


External links

* Tetramethylgermaniu
Datasheet commercial supplier
* Tetraethylgermaniu
Datasheet commercial supplier
* Tris(trimethylsilyl)germanium hydrid
Datasheet commercial supplier


References

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