Tricarbon (systematically named 1λ²,3λ²-propadiene and ''catena''-tricarbon) is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemi ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

(also written (μ-C)Cor ). It is a colourless gas that only persists in dilution or solution as an

adduct An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...

. It is one of the simplest unsaturated carbenes. Tricarbon can be found in interstellar space and can be produced in the laboratory by a process called

laser ablation Laser ablation or photoablation (also called laser blasting) is the process of removing material from a solid (or occasionally liquid) surface by irradiating it with a laser beam. At low laser flux, the material is heated by the absorbed laser ...

Natural occurrence

Tricarbon is a small

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

cluster first spectroscopically observed in the early 20th century in the tail of a comet by

William Huggins Sir William Huggins (7 February 1824 – 12 May 1910) was an English astronomer best known for his pioneering work in astronomical spectroscopy together with his wife, Margaret. Biography William Huggins was born at Cornhill, Middlesex, in ...

and subsequently identified in stellar atmospheres. Small carbon clusters like tricarbon and dicarbon are regarded as soot precursors and are implicated in the formation of certain industrial

diamond Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, ...

s and in the formation of

fullerene A fullerene is an allotrope of carbon whose molecule consists of carbon atoms connected by single and double bonds so as to form a closed or partially closed mesh, with fused rings of five to seven atoms. The molecule may be a hollow sphere, ...

s. C₃ has also been identified as a transient species in various

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combust ...

reactions.

Properties

Chemical properties

The chemical properties of C₃ was investigated in the 1960s by Professor Emeritus Philip S. Skell of

Pennsylvania State University The Pennsylvania State University (Penn State or PSU) is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers' High School of Pennsylvania, Penn State becam ...

, who showed that certain reactions of carbon vapor indicated its generation, such as the reaction with isobutylene to produce 1,1,1',1'-tetramethyl-bis-ethanoallene.

Physical properties

The ground state

molecular geometry Molecular geometry is the three-dimensional space, three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometric ...

of tricarbon has been identified as linear via its characteristic symmetric and antisymmetric stretching and bending vibrational modes and bears

bond length In molecular geometry, bond length or bond distance is defined as the average distance between nuclei of two bonded atoms in a molecule. It is a transferable property of a bond between atoms of fixed types, relatively independent of the rest ...

s of 129 to 130 picometer corresponding to those of

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s. The

ionization potential Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule ...

is determined experimentally at 11 to 13.5

electronvolt In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacu ...

s. In contrast to the linear tricarbon molecule, the

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

is bent.

Nomenclature

The systematic names ''1λ²,3λ²-propadiene'', and ''μ-carbidodicarbon'', valid

IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...

names, are constructed according to the substitutive and additive nomenclatures, respectively. In appropriate contexts, tricarbon can be viewed as propadiene with four hydrogen atoms removed, or as propane with eight hydrogen atoms removed; and as such, ''propadienediylidene'' or ''propanetetraylidene'', respectively, may be used as a context-specific systematic names, according to substitutive nomenclature. By default, these names pay no regard to the radicality of the tricarbon molecule. In even more specific context, these can also name the non-radical singlet state, whereas the diradical state is named ''propadienediylylidene'', or ''propanediyldiylidene'', and the tetraradical state is named ''propedienetetrayl'' or ''propanetetraylylidene''.Skell, P. S.; Wescott, L. D. (1963)

Natural occurrence

Properties

Chemical properties

Physical properties

Nomenclature

See also

References

Further reading