Carbon trioxide

Carbon trioxide (CO₃) is an unstable oxide of carbon (an oxocarbon). Three possible isomers of carbon trioxide, with molecular symmetry point groups C_s, D_3h, and C_2v, have been most studied by theoretical methods, and the C_2v state has been shown to be the ground state of the molecule.

Carbon trioxide should not be confused with the stable carbonate ion (CO₃²⁻).

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.

Another reported method is photolysis of ozone O₃ dissolved in liquid CO₂, or in CO₂/SF₆ mixtures at -45 °C, irradiated with light of 2537 Å. 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.

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).

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