What is "carbene"

n. (context organic chemistry English) Any short-lived, reactive species R₂C''':''', especially the parent compound CH₂''':''' (also called methylene).

In chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is R-(C:)-R' or R=C:.

The term "carbene" may also refer to the specific compound HC:, also called methylene, the parent hydride from which all other carbene compounds are formally derived. Carbenes are classified as either singlets or triplets, depending upon their electronic structure. Most carbenes are very short lived, although persistent carbenes are known. One well-studied carbene is dichlorocarbene ClC:, which can be generated in situ from chloroform and a strong base.