Provide an example of a carbene and a carbanion.

A carbene is a molecule containing a neutral carbon atom with two unshared valence electrons.

Carbenes are highly reactive and can participate in a variety of reactions, such as insertion into C-H bonds, cyclopropanation, and olefin metathesis. One example of a carbene is methylene (CH2), which is generated by the thermal decomposition of diazomethane. Methylene is a highly reactive species and can insert into C-H bonds to form new carbon-carbon bonds.

A carbanion is a molecule containing a negatively charged carbon atom. Carbanions are also highly reactive and can participate in a variety of reactions, such as nucleophilic substitution and addition reactions. One example of a carbanion is the enolate anion, which is formed by deprotonation of a carbonyl compound with a strong base. Enolates are important intermediates in organic synthesis and can be used to form new carbon-carbon bonds.

Overall, carbene and carbanion chemistry are important areas of study in organic chemistry and have many applications in organic synthesis.