Oxygen anion

• Formula: O₂^-
• Molecular weight: 31.9993
• IUPAC Standard InChI: InChI=1S/HO2/c1-2/h1H/p-1 Copy

  
• IUPAC Standard InChIKey: OUUQCZGPVNCOIJ-UHFFFAOYSA-M Copy
• CAS Registry Number: 11062-77-4
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  View 3d structure (requires JavaScript / HTML 5)
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
  • Ion clustering data
  • Constants of diatomic molecules
• Options:
  • Switch to calorie-based units

Reaction thermochemistry data

Go To: Top, Gas phase ion energetics data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
B - John E. Bartmess
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

 +  = ( • )

By formula: O₂^- + O₂ = (O₂^- • O₂)

Free energy of reaction

 +  = ( • )

By formula: O₂^- + CO₂ = (O₂^- • CO₂)

Free energy of reaction

( • ) +  = ( • 2)

By formula: (O₂^- • H₂O) + H₂O = (O₂^- • 2H₂O)

Free energy of reaction

( • 2) +  = ( • 3)

By formula: (O₂^- • 2H₂O) + H₂O = (O₂^- • 3H₂O)

Free energy of reaction

 +  = ( • )

By formula: O₂^- + H₂O = (O₂^- • H₂O)

( • 7 • ) +  = ( • 8 • )

By formula: (O₂^- • 7N₂ • O₂) + N₂ = (O₂^- • 8N₂ • O₂)

( • 2) +  = ( • 3)

By formula: (O₂^- • 2N₂O) + N₂O = (O₂^- • 3N₂O)

( • 3) +  = ( • 4)

By formula: (O₂^- • 3N₂O) + N₂O = (O₂^- • 4N₂O)

( • 4) +  = ( • 5)

By formula: (O₂^- • 4N₂O) + N₂O = (O₂^- • 5N₂O)

( • 5) +  = ( • 6)

By formula: (O₂^- • 5N₂O) + N₂O = (O₂^- • 6N₂O)

( • ) +  = ( • 2)

By formula: (O₂^- • N₂O) + N₂O = (O₂^- • 2N₂O)

( • 2) +  = ( • 3)

By formula: (O₂^- • 2CH₄O) + CH₄O = (O₂^- • 3CH₄O)

( • 2) +  = ( • 3)

By formula: (O₂^- • 2C₂H₃N) + C₂H₃N = (O₂^- • 3C₂H₃N)

 +  = ( • )

By formula: O₂^- + N₂O = (O₂^- • N₂O)

( • 3) +  = ( • 4)

By formula: (O₂^- • 3C₂H₃N) + C₂H₃N = (O₂^- • 4C₂H₃N)

( • ) +  = ( • 2)

By formula: (O₂^- • CH₄O) + CH₄O = (O₂^- • 2CH₄O)

( • ) +  = ( • 2)

By formula: (O₂^- • C₂H₃N) + C₂H₃N = (O₂^- • 2C₂H₃N)

( • 2) +  = ( • 3)

By formula: (O₂^- • 2CO₂) + CO₂ = (O₂^- • 3CO₂)

( • 3) +  = ( • 4)

By formula: (O₂^- • 3CO₂) + CO₂ = (O₂^- • 4CO₂)

( • 4) +  = ( • 5)

By formula: (O₂^- • 4CO₂) + CO₂ = (O₂^- • 5CO₂)

( • 5) +  = ( • 6)

By formula: (O₂^- • 5CO₂) + CO₂ = (O₂^- • 6CO₂)

( • 6) +  = ( • 7)

By formula: (O₂^- • 6CO₂) + CO₂ = (O₂^- • 7CO₂)

( • ) +  = ( • 2)

By formula: (O₂^- • CO₂) + CO₂ = (O₂^- • 2CO₂)

 +  = ( • )

By formula: O₂^- + CH₄O = (O₂^- • CH₄O)

 +  = ( • )

By formula: O₂^- + C₂H₃N = (O₂^- • C₂H₃N)

( • 6) +  = ( • 7)

By formula: (O₂^- • 6O₂) + O₂ = (O₂^- • 7O₂)

 +  = ( • )

By formula: O₂^- + N₂ = (O₂^- • N₂)

 +  = ( • )

By formula: O₂^- + CO = (O₂^- • CO)

( • 2 • ) +  = ( • 3 • )

By formula: (O₂^- • 2N₂ • O₂) + N₂ = (O₂^- • 3N₂ • O₂)

( • 3 • ) +  = ( • 4 • )

By formula: (O₂^- • 3N₂ • O₂) + N₂ = (O₂^- • 4N₂ • O₂)

( • 4 • ) +  = ( • 5 • )

By formula: (O₂^- • 4N₂ • O₂) + N₂ = (O₂^- • 5N₂ • O₂)

( • 5 • ) +  = ( • 6 • )

By formula: (O₂^- • 5N₂ • O₂) + N₂ = (O₂^- • 6N₂ • O₂)

( • 6 • ) +  = ( • 7 • )

By formula: (O₂^- • 6N₂ • O₂) + N₂ = (O₂^- • 7N₂ • O₂)

( •  • ) +  = ( • 2 • )

By formula: (O₂^- • N₂ • O₂) + N₂ = (O₂^- • 2N₂ • O₂)

( • 4294967295) +  =

By formula: (O₂^- • 4294967295O) + O = O₂^-

 +  =

By formula: O₂^- + H⁺ = HO₂

( • ) +  = ( •  • )

By formula: (O₂^- • O₂) + N₂ = (O₂^- • N₂ • O₂)

( • 3) +  = ( • 4)

By formula: (O₂^- • 3H₂O) + H₂O = (O₂^- • 4H₂O)

( • 2) +  = ( • 3)

By formula: (O₂^- • 2O₂) + O₂ = (O₂^- • 3O₂)

( • 3) +  = ( • 4)

By formula: (O₂^- • 3O₂) + O₂ = (O₂^- • 4O₂)

( • 4) +  = ( • 5)

By formula: (O₂^- • 4O₂) + O₂ = (O₂^- • 5O₂)

( • 5) +  = ( • 6)

By formula: (O₂^- • 5O₂) + O₂ = (O₂^- • 6O₂)

( • ) +  = ( • 2)

By formula: (O₂^- • O₂) + O₂ = (O₂^- • 2O₂)

( • ) +  = ( •  • )

By formula: (O₂^- • H₂O) + CO₂ = (O₂^- • CO₂ • H₂O)

Free energy of reaction

 +  = C₅H₅NO₂^-

By formula: O₂^- + C₅H₅N = C₅H₅NO₂^-

 +  = C₆H₆O₂^-

By formula: O₂^- + C₆H₆ = C₆H₆O₂^-

 +  = C₁₀H₈O₂^-

By formula: O₂^- + C₁₀H₈ = C₁₀H₈O₂^-

 +  = ( • )

By formula: O₂^- + Ar = (O₂^- • Ar)

( • 4) +  = ( • 5)

By formula: (O₂^- • 4H₂O) + H₂O = (O₂^- • 5H₂O)

Gas phase ion energetics data

Go To: Top, Reaction thermochemistry data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: John E. Bartmess

Protonation reactions

 +  =

By formula: O₂^- + H⁺ = HO₂

References

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Hiraoka, 1988
Hiraoka, K., A Determination of the Stabilities of O2+(O2)n and O2-(O2)n with n = 1 - 8 from Measurements of the Gas-Phase Ion Equilibria, J. Chem. Phys., 1988, 89, 5, 3190, https://doi.org/10.1063/1.454976 . [all data]

Conway and Nesbit, 1968
Conway, D.C.; Nesbit, L.E., Stability of O₄^-, J. Chem. Phys., 1968, 48, 1, 509, https://doi.org/10.1063/1.1667956 . [all data]

Hiraoka, 1888
Hiraoka, K., A Determination of the Stability of O₂⁺(O₂)n and O₂^-(O₂)n with n=1-8 from Measurements of the Gas Phase Ion Equilibria, J. Chem. Phys., 1888, 89, 5, 3190, https://doi.org/10.1063/1.454976 . [all data]

Sherwood, Hanold, et al., 1996
Sherwood, C.R.; Hanold, K.A.; Garner, M.C.; Strong, K.M.; Continetti, R.E., Translational Spectroscopy Studies of the Photodissociation Dynamics of O4-, J. Chem. Phys., 1996, 105, 24, 10803, https://doi.org/10.1063/1.472888 . [all data]

Aquino, Taylor, et al., 2001
Aquino, A.J.A.; Taylor, P.R.; Walch, S.P., Structure, properties, and photodissociation of O-4(-), J. Chem. Phys., 2001, 114, 7, 3010-3017, https://doi.org/10.1063/1.1288379 . [all data]

Payzant J.D. and Kebarle, 1972
Payzant J.D.; Kebarle, P., Kinetics and Reactions Leading to O2-(H2O)n in Moist Oxygen, J. Chem. Phys., 1972, 56, 7, 3482, https://doi.org/10.1063/1.1677723 . [all data]

Pack and Phelps, 1971
Pack, J.L.; Phelps, A.V., Hydration of Oxygen Negative Ions, Bull. Am. Phys. Soc., 1971, 16, 214. [all data]

Parkes, 1971
Parkes, D.A., Electron Attachment and Negative Ion-Molecule Reactions in Pure O₂, Trans. Farad. Soc., 1971, 97, 711, https://doi.org/10.1039/tf9716700711 . [all data]

Hiraoka and Yamabe, 1992
Hiraoka, K.; Yamabe, S., Formation of the Chelate Bonds in the Cluster O2(-)(CO2)n, CO3(-)(CO2)n, and NO2(-)(CO2)n, J. Chem. Phys., 1992, 97, 1, 643, https://doi.org/10.1063/1.463560 . [all data]

Pack and Phelps, 1966
Pack, J.L.; Phelps, A.V., Electron Attachment and Detachment . II. Mixtures of O₂ and CO₂ and of O₂ and H₂O, J. Chem. Phys., 1966, 45, 11, 4316, https://doi.org/10.1063/1.1727491 . [all data]

Vestal and Mauclaire, 1977
Vestal, M.L.; Mauclaire, G.H., Photodissociaton of negative ions formed in CO₂ and CO₂/O₂ Mixtures, J. Chem. Phys., 1977, 67, 3758. [all data]

Adams and Bohme, 1970
Adams, N.G.; Bohme, D., Flowing Afterglow Studies of Formation and Reactions of Cluster Ions of O₂⁺, O₂^-, and O^-, J. Chem. Phys., 1970, 52, 6, 3133, https://doi.org/10.1063/1.1673449 . [all data]

Fehsenfeld and Ferguson, 1974
Fehsenfeld, F.C.; Ferguson, E.E., Laboratory studies of negative ion reactions with atmospheric trace constituents, J. Chem. Phys., 1974, 61, 3181. [all data]

Arshadi and Kebarle, 1970
Arshadi, M.; Kebarle, P., Hydration of OH^- and O₂^- in the Gas Phase. Comparative Solvation of OH^- by Water and the Hydrogen Halides. Effect of Acidity, J. Phys. Chem., 1970, 74, 7, 1483, https://doi.org/10.1021/j100702a015 . [all data]

Kebarle, Arshadi, et al., 1968
Kebarle, P.; Arshadi, M.; Scarborough, J., Hydration of Negative Ions in the Gas Phase, J. Chem. Phys., 1968, 49, 2, 817, https://doi.org/10.1063/1.1670145 . [all data]

Luong, Clements, et al., 2001
Luong, A.K.; Clements, T.G.; Resat, M.S.; Continetti, R.E., Energetics and dissociative photodetachment dynamics of superoxide-water clusters: O-2(-)(H2O)(n), n=1-6, J. Chem. Phys., 2001, 114, 8, 3449-3455, https://doi.org/10.1063/1.1342221 . [all data]

Hiraoka, 1988, 2
Hiraoka, K., Determination of the Stabilities of O₃^-(N₂)n, O₃^-(O₂)n, and O₄^-(N₂)n from Measurements of the Gas Phase Equilibria, Chem. Phys., 1988, 125, 2-3, 439, https://doi.org/10.1016/0301-0104(88)87096-4 . [all data]

Hiraoka, Fujimaki, et al., 1994
Hiraoka, K.; Fujimaki, S.; Aruga, K.; Yamabe, S., Gas-phase clustering reactions of O2(-), NO-, and O- with N2O: Isomeric structures for (NO-N2O)(-), J. Phys. Chem., 1994, 98, 34, 8295, https://doi.org/10.1021/j100085a006 . [all data]

Yamdagni, Payzant, et al., 1973
Yamdagni, R.; Payzant, J.D.; Kebarle, P., Solvation of Cl- and O₂- with H₂O, CH₃OH, and CH₃CN in the gas phase, Can. J. Chem., 1973, 51, 2507. [all data]

Posey and Johnson, 1988
Posey, L.A.; Johnson, M.A., Pulsed Photoelectron Spectroscopy of Negative Cluster Ions: Isolation of Three Distinguishable Forms of N₂O₂^-, J. Chem. Phys., 1988, 88, 9, 5385, https://doi.org/10.1063/1.454576 . [all data]

Ervin, Anusiewicz, et al., 2003
Ervin, K.M.; Anusiewicz, W.; Skurski, P.; Simons, J.; Lineberger, W.C., The only stable state of O-2(-) is the X (2)Pi(g) ground state and it (still!) has an adiabatic electron detachment energy of, J. Phys. Chem. A, 2003, 107, 41, 8521-8529, https://doi.org/10.1021/jp0357323 . [all data]

Travers, Cowles, et al., 1989
Travers, M.J.; Cowles, D.C.; Ellison, G.B., Reinvestigation of the Electron Affinities of O2 and NO, Chem. Phys. Lett., 1989, 164, 5, 449, https://doi.org/10.1016/0009-2614(89)85237-6 . [all data]

Le Barbu, Schiedt, et al., 2002
Le Barbu, K.; Schiedt, J.; Weinkauf, R.; Schlag, E.W.; Nilles, J.M.; Xu, S.J.; Thomas, O.C.; Bowen, K.H., Microsolvation of small anions by aromatic molecules: An exploratory study, J. Chem. Phys., 2002, 116, 22, 9663-9671, https://doi.org/10.1063/1.1475750 . [all data]

Bowen and Eaton, 1988
Bowen, K.H.; Eaton, J.G., Photodetachment Spectroscopy of Negative Cluster Ions, in The Structure of Small Molecules and Ions, Ed. R. Naaman, Z. Vager, Plenum NY, 1988, 1988, p.147-169. [all data]

Notes

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, References

• Symbols used in this document:
  

  T	Temperature
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔrS°	Entropy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
• The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
• Customer support for NIST Standard Reference Data products.

© 2026 by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Copyright for NIST Standard Reference Data is governed by the Standard Reference Data Act.