The electrically neutral species
H2C:
and its derivatives, in which the carbon is covalently bonded to two univalent groups of any kind or a divalent group and bears two nonbonding electrons, which may be spin-paired (
singlet state) or spin-non-paired (
triplet state). In
systematic name formation, carbene is the name of the
parent hydride
:CH2
hence, the name dichlorocarbene for
:CCl2.
However, names for acyclic and cyclic
hydrocarbons containing one or more divalent carbon atoms are derived from the name of the corresponding all-

-hydrocarbon using the suffix -ylidene. E.g. prop-2-en-1-ylidene,
H2C=CHCH:
ethenylidene,
H2C=C:;
cyclohexylidene, Subclasses of carbenes include
acyl carbenes
,
imidoyl carbenes,
and
vinyl carbenes.
Source:
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995))
on page 1324
See also:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1092