A carbene is a neutral molecule which contains a carbon atom with an electron valency of 6 (two bonds and two nonbonding electrons). They are a very reactive type of compound, often too reactive to be observed. There are two forms of carbene:
The two types of carbene are different, not only in their stucture and electron distribution but also in reactivity.
- Triplet carbenes - have two unpaired electrons, one in an 'sp2' orbital, one in a 'p' orbital.
- Singlet carbenes - have a lone pair in a nonbonding 'sp2' orbital, and an empty 'p' orbital.