Iridium Sesquiselenide, Ir₂Se₃

Iridium Sesquiselenide, Ir₂Se₃, is obtained as a black precipitate by the action of hydrogen selenide upon a hot solution of iridium trichloride.

It is amorphous, insoluble in nitric acid even on warming, but slowly attacked by fuming nitric acid in sealed tubes at 250° C. and by aqua regia.

A compound of selenium and iridium, but of indefinite composition, is obtained by heating the two elements together at red heat in sealed tubes. The product is black, and very resistant to acid attack.