Organogallium chemistry is the chemistry of organometallic compounds containing a carbon
to gallium (Ga) chemical bond.
Despite their high toxicity, organogallium compounds have some use in organic synthesis.
The compound trimethylgallium is of some relevance to MOCVD as a precursor to gallium arsenide
via its reaction with arsine at 700 °C: Ga(CH3)3 + AsH3 → GaAs + 3CH4Gallium trichloride
is an important reagent for the introduction of gallium into organic compounds.
The main gallium oxidation state is Ga(III), as in all lower group 13 elements (such as
aluminium).
== Organogallium(III) chemistry == Compounds of the type R3Ga are monomeric.
Lewis acidity decreases in the order Al > Ga > In and as a result organogallium compounds
do not form bridged dimers as organoaluminum compounds do.
Organogallium compounds are also less reactive than organoaluminum compounds.
They do form stable peroxides.Organogallium compounds can be synthesized by transmetallation,
for example the reaction of gallium metal with dimethylmercury:
2Ga + 3Me2Hg → 2Me3Ga + 3 Hgor via organolithium compounds or Grignards:
GaCl3 + 3MeMgBr → Me3Ga + 3MgBrClThe electron-deficient nature of gallium can be removed by complex
formation, for example
Me2GaCl + NH3 → [Me2Ga(NH3)Cl]+Cl−Pi complex formation with alkynes is also known.
Organogallium compounds are reagents or intermediates in several classes of organic reactions:
Barbier-type reactions with elemental gallium, allylic substrates and carbonyl compounds
Carbometallation (carbogallation) reactions
== Higher group 13 organometallic chemistry ==
The chemistry of organoindium (In) and organothallium (Tl) compounds parallel that of organogallium
in many regards.
Indium and thallium in oxidation state +1 are more common, for example the metallocenes
cyclopentadienylindium(I) and cyclopentadienylthallium.
Trimethylindium is important in the semiconductor industry.
A special thallium feature is electrophilic thallation of arene compounds, reminiscent
of mercuration (the group 12 neighbor).
A common reagent for this purpose is thallium(III) trifluoroacetate.
The intermediate arylthallium bisfluoroacetate can be isolated and converted to an aryl halide,
aryl cyanide, aryl thiol or nitroarene.
An example is the iodation of para-xylene.
:A specific niche indium research topic is indium mediated allylation