Indium(III) hydroxide


Indium hydroxide is the chemical compound with the formula In3, its prime use is as a precursor to indium oxide, In2O3. It is sometimes found as the rare mineral dzhalindite.

Structure

In3 has a cubic structure, space group Im3, a distorted ReO3 structure.

Preparation and reactions

Neutralising a solution of an In3+ salt such as In3, indium nitrate or a solution of InCl3 gives a white precipitate that on ageing forms In3. A thermal decomposition of freshly prepared In3 shows the first step is the conversion of In3.\mathitH2O to cubic In3
The precipitation of indium hydroxide was a step in the separation of indium from zincblende ore by Reich and Richter the discoverers of indium.
In3 is amphoteric, like Ga3 and Al3 but is much less acidic than Ga3 having a lower solubility in alkali than in acid and is for all intents and purposes a basic hydroxide.
Dissolving In3 in strong alkali gives solutions that probably contain either four coordinate In4− or In4−
Reaction with acetic acid or carboxylic acids is likely to give the basic acetate or carboxylate salt, e.g. In2.
At 10MPa pressure and 250-400 °C In3 converts to indium oxide hydroxide, InO
Rapid decompression of samples of In3 compressed at 34 GPa causes decomposition, yielding some indium metal
Laser ablation of In3 gives InOH, indium hydroxide, a bent molecule with an In-O-H angle of around 132 ° and an In-O bond length of 201.7 pm