Chemical compound

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+
by infrared photodissociation spectroscopy with formal oxidation state +9 has been reported, the highest currently known of any element.[3][4]


  1. ^ Gong, Yu; Zhou, Mingfei; Kaupp, Martin; Riedel, Sebastian (2009). "Formation and Characterization of the Iridium Tetroxide Molecule with Iridium in the Oxidation State +VIII". Angewandte Chemie International Edition. 48 (42): 7879–7883. doi:10.1002/anie.200902733. PMID 19593837.
  2. ^ Citra, Angelo; Andrew, Lester (1999). "Reactions of Laser-Ablated Iridium Atoms with O2. Infrared Spectra and DFT Calculations for Iridium Dioxide and Peroxoiridium(VI) Dioxide in Solid Argon". J. Phys. Chem. A. 103 (21): 4182–4190. Bibcode:1999JPCA..103.4182C. doi:10.1021/jp990388o.
  3. ^ Himmel, D.; Knapp, C.; Patzschke, M.; Riedel, S. (2010). "How far can we go? Quantum-chemical investigations of oxidation state IX". ChemPhysChem. 11 (4): 865–869. doi:10.1002/cphc.200900910. PMID 20127784.
  4. ^ Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary J.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian (23 October 2014). "Identification of an iridium-containing compound with a formal oxidation state of IX". Nature. 514 (7523): 475–477. Bibcode:2014Natur.514..475W. doi:10.1038/nature13795. PMID 25341786. S2CID 4463905.