This dark red solid is the ammonium salt of the iridium(IV) complex [IrCl6]2−.

[3] The compound is prepared in the laboratory by the addition of ammonium chloride to an aqueous solution of sodium hexachloroiridate.

Upon heating under hydrogen, the solid salt converts to the metal:[1] The electronic structure of ammonium hexachloroiridate(IV) has attracted much attention.

This result is attributed to antiferromagnetic coupling between Ir centers mediated by Cl---Cl interactions.

Electron spin resonance studies reveal that more than half of the spin density resides on chloride, thus the description of the complex as Ir(IV) is an oversimplification.