Gallium halides

There are three sets of gallium halides, the trihalides where gallium has oxidation state +3, the intermediate halides containing gallium in oxidation states +1, +2 and +3 and some unstable monohalides, where gallium has oxidation state +1.

Trihalides

All four trihalides are known. They all contain gallium in the +3 oxidation state. Their proper names are gallium(III) fluoride, gallium(III) chloride, gallium(III) bromide and gallium(III) iodide.

Intermediate halides

Intermediate chlorides, bromides and iodides exist. They contain gallium in oxidation states +1, +2 and +3.

Monohalides

None of the monohalides are stable at room temperature. The previously reported GaBr and GaI produced from fusing gallium with the trihalide have been shown to be mixtures of metallic gallium with, respectively, Ga₂Br₃ and Ga₂I₃.

Anionic halide complexes

Salts containing GaCl₄⁻, GaBr₄⁻ and GaI₄⁻ are all known. Gallium is very different from indium in that it is only known to form 6 coordinate complexes with the fluoride ion. This can be rationalised by the smaller size of gallium (ionic radii of Ga(III) 62 pm, In(III) 80 pm).
Salts containing the Ga₂Cl₆²⁻ anion, where gallium has an oxidation state of +2, are known.