Iridium tetroxide

Iridium tetroxide (IrO₄, Iridium(VIII) oxide) is a binary compound of oxygen and iridium in oxidation state +8.^[1] This compound was formed by photochemical rearrangement of [(η¹-O₂)IrO₂] in solid argon at a temperature of 6 K (−267.15 °C; −448.87 °F). At higher temperatures, the oxide is unstable.^[2] The detection of the iridium tetroxide cation IrO⁺
₄ by infrared photodissociation spectroscopy with formal oxidation state +9 has been reported, the highest currently known of any element.^[3][4] However no salts are known, as attempted production of an Ir(IX) salt such as IrO₄SbF₆ did not result in anything.

Iridium(VIII) oxide

Names
IUPAC name Iridium(VIII) oxide
Identifiers
CAS Number	474103-25-8
3D model (JSmol)	Interactive image
InChI InChI=1S/Ir.4O Key: WIFDYPVIKSJTTM-UHFFFAOYSA-N
SMILES O=[Ir](=O)(=O)=O
Properties
Chemical formula	IrO4
Molar mass	256.213 g·mol−1
Melting point	−267.15 °C (−448.87 °F; 6.00 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references