:Carbon trioxide

{{About||polyatomic ion CO{{sup sub|2−|3}}|Carbonate|the UK postal district|CO postcode area}}

{{Chembox

| Name = Carbon trioxide

| ImageFile = File:Carbon trioxide.svg

| ImageFile1 = File:Co3-geometries.png

| ImageCaption1 = The C_s, D_3h, and C_2v isomers of carbon trioxide

| OtherNames = C_s isomer:

• Oxidooxymethanone
• Peroxycarbonite radical

| IUPACName = Carbon trioxide
C_2v isomer:

• Dioxiran-3-one

D_3h isomer:

• Carbonate radical

| SystematicName = C_2v isomer:

• Peroxycarbonic anhydride

D_3h isomer:

• Trioxidocarbon(2•)

| Section1 = {{Chembox Identifiers

| CASNo = 12144-05-7

| PubChem = 19817254

| SMILES = O=[C]O[O]

| SMILES_Comment = C_s

| SMILES1 = O=C([O])[O]

| SMILES1_Comment = D_3h

| SMILES2 = O=C1OO1

| SMILES2_Comment = C_2v

| StdInChI=1S/CO3/c2-1-3-4-1

| StdInChIKey = NPDDCAZCWJWIBW-UHFFFAOYSA-N

}}

| Section2 = {{Chembox Properties

| C=1 | O=3

| Appearance =

| Density =

| MeltingPt =

| BoilingPt =

| Solubility =

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| Section3 =

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Carbon trioxide (CO₃) is an unstable oxide of carbon (an oxocarbon). The possible isomers of carbon trioxide include ones with molecular symmetry point groups C_s, D_3h, and C_2v. The C_2v state, consisting of a dioxirane, has been shown to be the ground state of the molecule.

{{cite journal

|author1= T. Kowalczyk

|author2=A. I. Krylov

|date=Aug 2007

| title = Electronic structure of carbon trioxide and vibronic interactions involving Jahn–Teller states

| journal = J. Phys. Chem. A

| volume = 111

| pages = 8271–8276

| doi = 10.1021/jp073627d

| pmid = 17661455

| issue = 33

| issn = 1089-5639

|bibcode= 2007JPCA..111.8271K

}} Carbon trioxide should not be confused with the stable carbonate ion ({{chem|CO|3|2−}}).

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.

{{cite journal

| title = A theoretical study of the structure and properties of carbon trioxide

| journal = Chemical Physics Letters

| volume = 11

| issue = 5

| pages = 593–597

| bibcode = 1971CPL....11..593S

| doi = 10.1016/0009-2614(71)87010-0

| year = 1971

| author1 = Sabin, J. R

| author2 = Kim, H

}}

Another reported method is photolysis of ozone O₃ dissolved in liquid CO₂, or in CO₂/SF₆ mixtures at {{cvt|−45|C|K F}}, irradiated with light of 253.7 nm. The formation of CO₃ is inferred but it appears to decay spontaneously by the route

:2 CO₃ → 2 CO₂ + O₂

with a lifetime much shorter than 1 minute.

{{cite journal

| title = Formation of carbon trioxide in the photolysis of ozone in liquid carbon dioxide

|author1=DeMore W. B. |author2=Jacobsen C. W. | pages = 2935–2938

| doi = 10.1021/j100843a026

| year = 1969

| volume =73

| issue =9

| journal =Journal of Physical Chemistry

}}

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 C_2v isomer,{{cite journal|doi=10.1039/b315626p|title=Untangling the formation of the cyclic carbon trioxide isomer in low temperature carbon dioxide ices|journal=Physical Chemistry Chemical Physics|volume=6|issue=4|pages=735|year=2004|last1=Bennett|first1=Chris J.|last2=Jamieson|first2=C.|last3=Mebel|first3=Alexander M.|last4=Kaiser|first4=Ralf I.|s2cid=51769127|bibcode=2004PCCP....6..735B}} the first spectroscopic detection of the D_3h isomer was in electron-irradiated ices of carbon dioxide.{{cite journal|doi=10.1002/cphc.200600390|pmid=17029325|title=Identification of the D_3h Isomer of Carbon Trioxide (CO₃) and Its Implications for Atmospheric Chemistry|journal=ChemPhysChem|volume=7|issue=12|pages=2508–2513|year=2006|last1=Jamieson|first1=Corey S.|last2=Mebel|first2=Alexander M.|last3=Kaiser|first3=Ralf I.}}