Editing Gallium (section)

===Organogallium compounds===
{{Main|Organogallium chemistry}}
Organogallium compounds are of similar reactivity to [[Organoindium chemistry|organoindium]] compounds, less reactive than [[Organoaluminium chemistry|organoaluminium]] compounds, but more reactive than [[Thallium#Organothallium compounds|organothallium]] compounds.<ref name="GreenwoodEarnshaw2nd"/>{{rp|262-5}} Alkylgalliums are monomeric. [[Lewis acid]]ity decreases in the order Al > Ga > In and as a result organogallium compounds do not form bridged dimers as organoaluminium compounds do. Organogallium compounds are also less reactive than organoaluminium compounds. They do form stable peroxides.<ref>{{cite journal |last1=Uhl |first1=Werner |last2=Reza Halvagar |first2=Mohammad |last3=Claesener |first3=Michael |title=Reducing Ga-H and Ga-C Bonds in Close Proximity to Oxidizing Peroxo Groups: Conflicting Properties in Single Molecules |journal=Chemistry – A European Journal |date=26 October 2009 |volume=15 |issue=42 |pages=11298–11306 |doi=10.1002/chem.200900746 |pmid=19780106 }}</ref> These alkylgalliums are liquids at room temperature, having low melting points, and are quite mobile and flammable. Triphenylgallium is monomeric in solution, but its crystals form chain structures due to weak intermolecluar Ga···C interactions.<ref name="GreenwoodEarnshaw2nd"/>{{rp|262-5}}

Gallium trichloride is a common starting reagent for the formation of organogallium compounds, such as in [[carbometalation|carbogallation]] reactions.<ref>{{cite journal |doi= 10.1002/ejoc.200500512 |volume=2005 |issue=24 |title=GaCl<sub>3</sub> in Organic Synthesis |year=2005 |journal=European Journal of Organic Chemistry |pages=5145–5150 |last1= Amemiya |first1= Ryo}}</ref> Gallium trichloride reacts with [[lithium]] cyclopentadienide in [[diethyl ether]] to form the trigonal planar gallium cyclopentadienyl complex GaCp<sub>3</sub>. Gallium(I) forms complexes with [[arene]] [[ligand]]s such as [[hexamethylbenzene]]. Because this ligand is quite bulky, the structure of the [Ga(η<sup>6</sup>-C<sub>6</sub>Me<sub>6</sub>)]<sup>+</sup> is that of a [[half sandwich compound|half-sandwich]]. Less bulky ligands such as [[mesitylene]] allow two ligands to be attached to the central gallium atom in a bent sandwich structure. [[Benzene]] is even less bulky and allows the formation of dimers: an example is [Ga(η<sup>6</sup>-C<sub>6</sub>H<sub>6</sub>)<sub>2</sub>] [GaCl<sub>4</sub>]·3C<sub>6</sub>H<sub>6</sub>.<ref name="GreenwoodEarnshaw2nd"/>{{rp|262-5}}