organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, thioketenes are

organosulfur compound Organosulfur chemistry is the study of the properties and synthesis of organosulfur compounds, which are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur der ...

s analogous to

ketene In organic chemistry, a ketene is an organic compound of the form , where R and R' are two arbitrary valence (chemistry), monovalent functional group, chemical groups (or two separate Substituent, substitution sites in the same molecule). The na ...

s with the general formula , where R is

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cy ...

aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used ...

. The parent thioketene (ethenthione) has the formula . It is the simplest thioketene. Ethenthione is stable as a gas, but like most thioketenes, it polymerizes upon condensation. Some thioketenes are produced as transient species upon

pyrolysis Pyrolysis is a process involving the Bond cleavage, separation of covalent bonds in organic matter by thermal decomposition within an Chemically inert, inert environment without oxygen. Etymology The word ''pyrolysis'' is coined from the Gree ...

of 1,2,3-thiadiazoles. It has been suggested that thioketenes could be involved in cell damage processes.

Isolable thioketenes

Thioketenes can be stabilized by either steric protection or by electronic effects. Thus, di-tert-butylthioketene is easily isolated and air-stable. Several examples have been characterized by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

. The C=S distance is 157 pm and the C=C distance is 124 pm, both bonds being suitable for the C=C=S assignment. The violet color characteristic of thioketenes indicates the small HOMO-LUMO gap. These compound are prepared by treatment of the acid chloride with

phosphorus pentasulfide Phosphorus pentasulfide is the inorganic compound with the formula (empirical) or ( molecular). This yellow solid is the one of two phosphorus sulfides of commercial value. Samples often appear greenish-gray due to impurities. It is soluble in ...

as described by the following idealized equation: : Bis(trifluoromethyl)thioketene () is an example of an electronically stabilized thioketene.

Reactions

Thioketenes are electrophilic. They add amines to give thioamides: : With peroxyacids, they produce thioketene-S-oxides: : Thioketenes bind to metal carbonyls giving adducts.

Related compounds

* carbon subsulfide ({{chem2, S\dC\dC\dC\dS).

References

Sulfur(−II) compounds Ketenes Functional groups