Carbon trioxide (CO3) is an unstable oxide of carbon (an oxocarbon). Three possible isomers of carbon trioxide, with molecular symmetry point groups Cs, D3h, and C2v, have been most studied by theoretical methods, and the C2v state has been shown to be the ground state of the molecule.[1][2] Carbon trioxide should not be confused with the stable carbonate ion (CO32−).

Carbon trioxide
Carbon trioxide.svg
The Cs, D3h, and C2v isomers of carbon trioxide
3D model (JSmol)
Molar mass 60.008 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Carbon trioxide can be produced, for example, in the drift zone of a negative corona discharge by reactions between carbon dioxide (CO2) and the atomic oxygen (O) created from molecular oxygen by free electrons in the plasma.[3] Another reported method is photolysis of ozone O3 dissolved in liquid CO2, or in CO2/SF6 mixtures at -45 °C, irradiated with light of 253.7 nm. The formation of CO3 is inferred but it appears to decay spontaneously by the route 2CO3 → 2CO2 + O2 with a lifetime much shorter than 1 minute.[4] Carbon trioxide can be made by blowing ozone at dry ice (solid CO2), and it has also been detected in reactions between carbon monoxide (CO) and molecular oxygen (O2). Along with the ground state C2v isomer,[5] the first spectroscopic detection of the D3h isomer was in electron-irradiated ices of carbon dioxide.[6]


  1. ^ Tim Kowalczyk, Electronic structure and spectroscopy of carbon trioxide
  2. ^ T. Kowalczyk; A. I. Krylov (Aug 2007). "Electronic structure of carbon trioxide and vibronic interactions involving Jahn-Teller states". J. Phys. Chem. A. 111 (33): 8271–8276. Bibcode:2007JPCA..111.8271K. doi:10.1021/jp073627d. ISSN 1089-5639. PMID 17661455.
  3. ^ Sabin, J. R; Kim, H (1971). "A theoretical study of the structure and properties of carbon trioxide". Chemical Physics Letters. 11 (5, ): 593–597. Bibcode:1971CPL....11..593S. doi:10.1016/0009-2614(71)87010-0.CS1 maint: extra punctuation (link)
  4. ^ DeMore W. B.; Jacobsen C. W. (1969). "Formation of carbon trioxide in the photolysis of ozone in liquid carbon dioxide". Journal of Physical Chemistry. 73 (9): 2935–2938. doi:10.1021/j100843a026.
  5. ^ Bennett, Jamieson, Mebel, & Kaiser. "Untangling the formation of the cylic trioxide isomer in low temperature carbon dioxide ices", Physical Chemistry Chemical Physics, 2004, 6, 735
  6. ^ Jamieson, Mebel, & Kaiser. "Identification of the D3h isomer of carbon trioxide (CO3) and its implications for atmospheric chemistry", ChemPhysChem, 2006, 7, 2508.

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