What is the Difference Between Carbene and Carbanion?

Carbene and carbanion are both organic molecules containing carbon and hydrogen or other atoms, but they have distinct differences in their structure and properties. The main differences between carbene and carbanion are:

1. Valency: Carbene has a divalent carbon atom, whereas carbanion has a trivalent carbon atom.
2. Charge: Carbene is a neutral species, while carbanion is a negatively charged species.
3. Electron Density: Carbenes are electron-deficient and extremely reactive, undergoing a variety of unusual reactions. Carbanions, on the other hand, have a negative charge on the carbon atom, which makes them more stable and able to react with various reagents.
4. Geometry and Hybridization: In carbenes, the carbon atom is sp² hybridized, with a trigonal planar geometry and a bond angle of 120°. In carbanions, the carbon atom is sp³ hybridized, with a pyramidal geometry.
5. Stability: Carbanions can be classified into primary, secondary, and tertiary carbanions, with the stability order being primary > secondary > tertiary. The stability of a carbanion depends on the electron-withdrawing or electron-donating groups attached to the carbon atom.

In summary, carbenes are neutral species with a divalent carbon atom, while carbanions are negatively charged species with a trivalent carbon atom. Both species play important roles in organic chemistry and are widely used in various synthetic transformations.

Comparative Table: Carbene vs Carbanion

Carbene and carbanion are both organic molecules containing carbon and hydrogen or other atoms, but they have some key differences:

Carbenes contain a neutral carbon atom with a valence of two and two unshared electrons, while carbanions contain a negatively charged carbon atom with a valence of three. Carbenes have a general chemical formula of R-(C:)-R' or R=C:, and can be classified as either singlet or triplet carbenes depending on their electronic structure. On the other hand, carbanions have not been mentioned to have a specific structure or electronic configuration in the search results. Carbenes are highly reactive due to their unshared electrons, while carbanions can be stabilized by hydrogen bonding with a Lewis base.