Letter | Published:

Identification of an iridium-containing compound with a formal oxidation state of IX

Nature volume 514, pages 475477 (23 October 2014) | Download Citation

Abstract

One of the most important classifications in chemistry and within the periodic table is the concept of formal oxidation states1,2,3,4. The preparation and characterization of compounds containing elements with unusual oxidation states is of great interest to chemists5. The highest experimentally known formal oxidation state of any chemical element is at present VIII2,3,4, although higher oxidation states have been postulated6,7. Compounds with oxidation state VIII include several xenon compounds8 (for example XeO4 and XeO3F2) and the well-characterized species RuO4 and OsO4 (refs 2, 3, 4). Iridium, which has nine valence electrons, is predicted to have the greatest chance of being oxidized beyond the VIII oxidation state1. In recent matrix-isolation experiments, the IrO4 molecule was characterized as an isolated molecule in rare-gas matrices9. The valence electron configuration of iridium in IrO4 is 5d1, with a formal oxidation state of VIII. Removal of the remaining d electron from IrO4 would lead to the iridium tetroxide cation ([IrO4]+), which was recently predicted to be stable10 and in which iridium is in a formal oxidation state of IX. There has been some speculation about the formation of [IrO4]+ species11,12, but these experimental observations have not been structurally confirmed. Here we report the formation of [IrO4]+ and its identification by infrared photodissociation spectroscopy. Quantum-chemical calculations were carried out at the highest level of theory that is available today, and predict that the iridium tetroxide cation, with a Td-symmetrical structure and a d0 electron configuration, is the most stable of all possible [IrO4]+ isomers.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    Oxidation Numbers and Oxidation States (Springer, 1969)

  2. 2.

    & The highest oxidation states of the transition metal elements. Coord. Chem. Rev. 253, 606–624 (2009)

  3. 3.

    in Comprehensive Inorganic Chemistry II (eds & ) 187–221 (Elsevier, 2013)

  4. 4.

    & in Comprehensive Inorganic Chemistry Vol. 9 (ed. ) 227–243 (Elsevier, 2013)

  5. 5.

    New understanding of unusual oxidation states in the transition groups. Naturwissenschaften 63, 292 (1976)

  6. 6.

    , , & Could uranium(XII) hexoxide, UO6 (Oh) exist? Chem. Phys. Lett. 328, 415–419 (2000)

  7. 7.

    , , & Theoretical investigations of geometry, electronic structure and stability of UO6: octahedral uranium hexoxide and its isomers. J. Phys. Chem. A 114, 8837–8844 (2010)

  8. 8.

    & Solution multi-NMR and Raman spectroscopic studies of thermodynamically unstable XeO4. The first 131Xe NMR study of a chemically bound xenon species. Inorg. Chem. 41, 198–204 (2002)

  9. 9.

    , , & Formation and characterization of the iridium tetraoxide molecule with iridium in the oxidation state VIII. Angew. Chem. Int. Ed. 48, 7879–7883 (2009)

  10. 10.

    , , & How far can we go? Quantum-chemical investigations of oxidation state IX. ChemPhysChem 11, 865–869 (2010)

  11. 11.

    , & Chemical consequences of the 193Os(β)193Ir decay in osmium compounds studied by the Mössbauer method. Radiochim. Acta 11, 203–210 (1969)

  12. 12.

    , , & Gas-phase reactions of transition-metal ions with molecular oxygen: room-temperature kinetics and periodicities in reactivity. J. Phys. Chem. A 106, 4581–4590 (2002)

  13. 13.

    et al. Infrared photodissociation spectroscopy of mononuclear iron carbonyl anions. J. Phys. Chem. A 116, 2484–2489 (2012)

  14. 14.

    Infrared spectroscopy to probe structure and dynamics in metal ion-molecule complexes. Int. Rev. Phys. Chem. 22, 407–435 (2003)

  15. 15.

    , , & Infrared spectra of the solvated hydronium ion: vibrational predissociation spectroscopy of mass-selected H3O+·(H2O)n·(H2)m. J. Phys. Chem. 94, 3416–3427 (1990)

  16. 16.

    & High-resolution spectroscopy of cluster ions. Chem. Rev. 100, 3963–3998 (2000)

  17. 17.

    & Molecular aspects of halide ion hydration: the cluster approach. Annu. Rev. Phys. Chem. 54, 173–213 (2003)

  18. 18.

    , & A reassessment of the bond dissociation energies of peroxides. An ab initio study. J. Am. Chem. Soc. 118, 12758–12765 (1996)

  19. 19.

    & Bond energy of IrO+: guided ion-beam and theoretical studies of the reaction of Ir+ (5F) with O2. J. Phys. Chem. A 117, 7754–7766 (2013)

  20. 20.

    , & Spectroscopic and theoretical studies of transition metal oxides and dioxygen complexes. Chem. Rev. 109, 6765–6808 (2009)

  21. 21.

    , , & Infrared spectra and density functional calculations for MO2, MO3, (O2)MO2, MO4, MO2- (M = Re, Ru, Os) and ReO3-, ReO4- in solid neon and argon. J. Phys. Chem. A 104, 3457–3465 (2000)

  22. 22.

    , & Some observations on the reaction chemistry of dioxygenyl salts and on the blue and purple compounds believed to be ClF3O2. J. Fluor. Chem. 7, 543–549 (1976)

  23. 23.

    et al. Gaussian09, revision A.1 (Gaussian, Inc., 2009)

  24. 24.

    Density-functional exchange-energy approximation with correct asymptotic behavior. Phys. Rev. A 38, 3098–3100 (1988)

  25. 25.

    Density functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98, 5648–5652 (1993)

  26. 26.

    , & Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B 37, 785–789 (1988)

  27. 27.

    , & Validation of density functional methods for computing structures and energies of mercury(IV) complexes. Phys. Chem. Chem. Phys. 6, 1122–1127 (2004)

  28. 28.

    , , & A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 132, 154104 (2010)

  29. 29.

    , & Electron affinities of the first-row atoms revisited. Systematic basis sets and wave functions. J. Chem. Phys. 96, 6796–6806 (1992)

  30. 30.

    & Gaussian basis sets for use in correlated molecular calculations. III. The atoms aluminum through argon. J. Chem. Phys. 98, 1358–1371 (1993)

  31. 31.

    , , & Energy-consistent relativistic pseudopotentials and correlation consistent basis sets for the 4d elements Y–Pd. J. Chem. Phys. 126, 124101 (2007)

  32. 32.

    , , & Energy-consistent pseudopotentials and correlation consistent basis sets for the 5d elements Hf–Pt. J. Chem. Phys. 130, 164108 (2009)

  33. 33.

    Turbomole. Version 6.2, (TURBOMOLE Gmbh, 2011)

  34. 34.

    & Optimized Slater-type basis sets for the elements 1–118. J. Comput. Chem. 24, 1142–1156 (2003)

  35. 35.

    , & Relativistic regular two-component Hamiltonians. J. Chem. Phys. 99, 4597–4610 (1993)

  36. 36.

    ADF v 2013.01, (SCM, 2013)

  37. 37.

    , , & Towards an order-N DFT method. Theor. Chem. Acc. 99, 391–403 (1998)

  38. 38.

    et al. Chemistry with ADF. J. Comput. Chem. 22, 931–967 (2001)

  39. 39.

    et al. CFour 1.2 ed., (2010)

  40. 40.

    MOLPRO version 2008. 1, (2008)

  41. 41.

    & Oxidation states, atomic charges and orbital populations in transition metal complexes. Theor. Chem. Acc. 123, 67–73 (2009)

Download references

Acknowledgements

This work was supported by the Ministry of Science and Technology of China (2013CB834603 and 2012YQ220113-3), the National Natural Science Foundation of China (grant nos 21173053, 21433005 and 91026003), the Committee of Science and Technology of Shanghai (13XD1400800), the Fonds der Chemischen Industrie and the GRK 1582 ‘Fluorine as a key element’. We also acknowledge the Natural Sciences and Engineering Research Council of Canada for a Discovery Grant (G.J.S.) and for a postgraduate scholarship (J.T.G.). We are grateful to I. Krossing and H. Hillebrecht for their support.

Author information

Affiliations

  1. Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai 200433, China

    • Guanjun Wang
    •  & Mingfei Zhou
  2. Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada

    • James T. Goettel
    •  & Gary J. Schrobilgen
  3. Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China

    • Jing Su
    •  & Jun Li
  4. Institut für Anorganische und Analytische Chemie, Albert-Ludwigs Universität Freiburg, Albertstrasse 21, D-79104 Freiburg im Breisgau, Germany

    • Tobias Schlöder
    •  & Sebastian Riedel
  5. Institut für Chemie und Biochemie – Anorganische Chemie, Freie Universität Berlin, Fabeckstrasse 34-36, D-14195 Berlin, Germany

    • Sebastian Riedel

Authors

  1. Search for Guanjun Wang in:

  2. Search for Mingfei Zhou in:

  3. Search for James T. Goettel in:

  4. Search for Gary J. Schrobilgen in:

  5. Search for Jing Su in:

  6. Search for Jun Li in:

  7. Search for Tobias Schlöder in:

  8. Search for Sebastian Riedel in:

Contributions

G.W. and M.Z. designed and performed the gas-phase experiments, J.T.G. and G.J.S. attempted to synthesize [IrO4] salts, J.S., J.L., T.S. and S.R. performed the quantum chemical calculations. M.Z., G.J.S., J.L. and S.R. wrote the paper and supervised the experimental and theoretical parts. All authors discussed the results and commented on the manuscript at all stages.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Mingfei Zhou or Gary J. Schrobilgen or Sebastian Riedel.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains a Supplementary Discussion, Supplementary References, Supplementary Tables 1-8, Supplementary Figures 1-12.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature13795

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.