Dicarbon monoxide

Dicarbon monoxide (C2O) is a molecule that contains two carbon atoms and one oxygen atom. It is a linear molecule that, because of its simplicity, is of interest in a variety of areas. It is, however, so extremely reactive that it is not encountered in everyday life. It is classified as a cumulene and an oxocarbon.[1]

Dicarbon monoxide
Stick model of dicarbon monoxide
Spacefill model of dicarbon monoxide
Ball and stick model of dicarbon monoxide
IUPAC name
Other names
3D model (JSmol)
Molar mass 40.021 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).


Dicarbon monoxide is a product of the photolysis of carbon suboxide:[2][3]

C3O2 → CO + C2O

It is stable enough to observe reactions with NO and NO2.[4]

Called ketenylidene in organometallic chemistry, it is a ligand observed in metal carbonyl clusters, e.g. [OC2Co3(CO)9]+. Ketenylidenes are proposed as intermediates in the chain growth mechanism of the Fischer-Tropsch Process, which converts carbon monoxide and hydrogen to hydrocarbon fuels.[5]

The organophosphorus compound (C6H5)3PCCO (CAS# 15596-07-3) contains the C2O functionality. Sometimes called Bestmann's Ylide, it is a yellow solid.[6]


  1. ^ Frenking, Gernot; Tonner, Ralf "Divalent carbon(0) compounds" Pure and Applied Chemistry 2009, vol. 81, pp. 597-614. doi:10.1351/PAC-CON-08-11-03
  2. ^ Bayes, K. (1961). "Photolysis of Carbon Suboxide". Journal of the American Chemical Society. 83 (17): 3712–3713. doi:10.1021/ja01478a033.
  3. ^ Anderson, D. J.; Rosenfeld, R. N. (1991). "Photodissociation of Carbon Suboxide". Journal of Chemical Physics. 94 (12): 7857–7867. doi:10.1063/1.460121.
  4. ^ Thweatt, W. D.; Erickson, M. A.; Hershberger, J. F. (2004). "Kinetics of the CCO + NO and CCO + NO2 reactions". Journal of Physical Chemistry A. 108 (1): 74–79. doi:10.1021/jp0304125.
  5. ^ Jensen, Michael P.; Shriver, Duward F. "Carbon-carbon and carbonyl transformations in ketenylidene cluster compounds" Journal of Molecular Catalysis 1992, vol. 74, pp. 73-84. doi:10.1016/0304-5102(92)80225-6
  6. ^ H. J. Bestmann, R. Zimmermann, M. Riou "Ketenylidenetriphenylphosphorane" e-EROS Encyclopedia of Reagents for Organic Synthesis 2001. doi: 10.1002/047084289X.rk005.pub2
Aluminium(II) oxide

Aluminium(II) oxide or aluminium monoxide is a compound of aluminium and oxygen with the chemical formula AlO. It has been detected in the gas phase after explosion of aluminized grenades in the upper atmosphere and in stellar absorption spectra.


Benzonitrile is the chemical compound with the formula C6H5(CN), abbreviated PhCN. This aromatic organic compound is a colorless liquid with a sweet almond odour. It is mainly used as a precursor to the resin benzoguanamine.

Circumstellar envelope

A circumstellar envelope (CSE) is a part of a star that has a roughly spherical shape and is not gravitationally bound to the star core. Usually circumstellar envelopes are formed from the dense stellar wind, or they are present before the formation of the star. Circumstellar envelopes of old stars (Mira variables and OH/IR stars) eventually evolve into protoplanetary nebulae, and circumstellar envelopes of young stellar objects evolve into circumstellar discs.


Cyclopropenone is an organic compound with molecular formula C3H2O consisting of a cyclopropene carbon framework with a ketone functional group. It is a colorless, volatile liquid that boils near room temperature. Neat cyclopropenone polymerizes upon standing at room temperature. The chemical properties of the compound are dominated by the strong polarization of the carbonyl group, which gives a partial positive charge with aromatic stabilization on the ring and a partial negative charge on oxygen. It is an aromatic compound.

Ethyl formate

Ethyl formate is an ester formed when ethanol (an alcohol) reacts with formic acid (a carboxylic acid). Ethyl formate has the characteristic smell of rum and is also partially responsible for the flavor of raspberries. It occurs naturally in the body of ants and in the stingers of bees.

Intergalactic dust

Intergalactic dust is cosmic dust in between galaxies in intergalactic space. Evidence for intergalactic dust has been suggested as early as 1949, and study of it grew throughout the late 20th century. There are large variations in the distribution of intergalactic dust. The dust may affect intergalactic distance measurements, such as to supernova and quasars in other galaxies.Intergalactic dust can form intergalactic dust clouds, known to exist around some galaxies since the 1960s. By the 1980s, at least four intergalactic dust clouds had been discovered within several megaparsec (Mpc) of the Milky Way galaxy, exemplified by the Okroy cloud.In February 2014, NASA announced a greatly upgraded database for tracking polycyclic aromatic hydrocarbons (PAHs) in the universe. According to scientists, more than 20% of the carbon in the universe may be associated with PAHs, possible starting materials for the formation of life. PAHs seem to have been formed as early as two billion years after the Big Bang, are widespread throughout the universe, and are associated with new stars and exoplanets.


Ketenimines are a group of organic compounds sharing a common functional group with the general structure R1R2C=C=NR3. A ketenimine is a cumulated alkene and imine and is related to an allene and a ketene.

The parent compound is ketenimine or CH2CNH. The most recent work by Bane et al. investigates the rovibrational structure of the ν8 and ν12 bands in the high-resolution FTIR spectrum, complementing the earlier analysis of the pure rotational spectrum. This pair of Coriolis coupled bands provide a rare example where intensity sharing between bands yields sufficient intensity for an otherwise invisible band (ν12).

Methoxy group

A methoxy group is the functional group consisting of a methyl group bound to oxygen. This alkoxy group has the formula O–CH3. On a benzene ring, the Hammett equation classifies a methoxy substituent as an electron-donating group.

Octatetraynyl radical

Octatetraynyl radical (C8H) is an organic free radical with eight carbon atoms linked in a chain with alternating single bonds and triple bonds.

In 2007 negatively charged octatetraynyl was detected in Galactic molecular source TMC-1, making it the second type of anion to be found in the interstellar medium (after Hexatriynyl radical) and the largest such molecule detected to date.

Phosphorus mononitride

Phosphorus mononitride is an inorganic compound with the chemical formula PN. Containing only phosphorus and nitrogen, this material is classified as a binary nitride.

It is the first identified phosphorus compound in the interstellar medium.It is an important molecule in interstellar medium and the atmospheres of Jupiter and Saturn.

Photodissociation region

Photodissociation regions (or photon-dominated regions, or PDRs) are predominantly neutral regions of the interstellar medium in which far ultraviolet photons strongly influence the gas chemistry and act as the most important source of heat. They occur in any region of interstellar gas that is dense and cold enough to remain neutral, but that has too low a column density to prevent the penetration of far-UV photons from distant, massive stars. A typical and well-studied example is the gas at the boundary of a giant molecular cloud. PDRs are also associated with HII regions, reflection nebulae, active galactic nuclei, and Planetary nebulae. All the atomic gas and most of the molecular gas in the galaxy is found in PDRs.


Propionaldehyde or propanal is the organic compound with the formula CH3CH2CHO. It is a saturated 3-carbon aldehyde and is a structural isomer of acetone. It is a colorless liquid with a slightly irritating, fruity odor.


Propynal is an organic compound with molecular formula HC2CHO. It is the simplest chemical compound containing both alkyne and aldehyde functional groups. It is a colorless liquid with explosive properties.The compound exhibits reactions expected for an electrophilic alkynyl aldehyde. It is a dienophile and a good Michael acceptor. Grignard reagents add to the carbonyl center.

Silicon monosulfide

Silicon monosulfide is a chemical compound of silicon and sulfur. The chemical formula is SiS. Molecular SiS has been detected at high temperature in the gas phase. The gas phase molecule has an Si-S bondlength of 192.93 pm, this compares to the normal single bond length of 216 pm, and is shorter than the Si=S bond length of around 201 pm reported in an organosilanethione. Historically a pale yellow-red amorphous solid compound has been reported. The behavior of silicon can be contrasted with germanium which forms a stable solid monosulfide.

Titanium oxide

Titanium oxide may refer to:

Titanium dioxide (titanium(IV) oxide), TiO2

Titanium(II) oxide (titanium monoxide), TiO, a non-stoichiometric oxide

Titanium(III) oxide (dititanium trioxide), Ti2O3



δ-TiOx (x= 0.68–0.75)

TinO2n−1 where n ranges from 3–9 inclusive, e.g. Ti3O5, Ti4O7, etc.

Triatomic molecule

Triatomic molecules are molecules composed of three atoms, of either the same or different chemical elements. Examples include H2O, CO2 (pictured) and HCN.

Tricarbon monoxide

Tricarbon monoxide C3O is a reactive radical oxocarbon molecule found in space, and which can be made as a transient substance in the laboratory. It can be trapped in an inert gas matrix or made as a short lived gas. C3O can be classified as a ketene or an oxocumulene a kind of heterocumulene.

Vinyl alcohol

Vinyl alcohol, also called ethenol (IUPAC name), is the simplest enol. With the formula CH2CHOH, it is a labile compound that converts to acetaldehyde. It is not a precursor to polyvinyl alcohol.

Common oxides
Exotic oxides
Compounds derived from oxides
Mixed oxidation states
+1 oxidation state
+2 oxidation state
+3 oxidation state
+4 oxidation state
+5 oxidation state
+6 oxidation state
+7 oxidation state
+8 oxidation state


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