What is the hybridization state of carbon in carbocation, carbanion and free radical?
The Correct Answer and Explanation is:
The hybridization state of carbon in a carbocation, carbanion, and free radical differs due to the different bonding and electron configurations. Let’s break it down for each species:
1. Carbocation (C⁺):
In a carbocation, the carbon atom has a positive charge and has only three bonds, leaving one empty orbital. Since there are only three bonds, the carbon atom has three regions of electron density around it. This suggests that the hybridization of the carbon atom in a carbocation is sp². The three regions of electron density (two single bonds and one empty p orbital) are arranged in a trigonal planar geometry with 120-degree bond angles. The empty p orbital is available for any possible interactions, but it doesn’t contribute to bonding.
2. Carbanion (C⁻):
In a carbanion, the carbon atom carries a negative charge, which means it has one extra electron. This extra electron occupies an orbital, increasing the number of regions of electron density around the carbon to four. As a result, the carbon atom in a carbanion undergoes sp³ hybridization. The four regions of electron density (three single bonds and one lone pair of electrons) are arranged in a tetrahedral geometry with 109.5-degree bond angles. The lone pair of electrons is in one of the hybrid orbitals, while the remaining orbitals form bonds with other atoms.
3. Free Radical (C·):
A free radical has one unpaired electron, and thus the carbon atom in a free radical also has three bonds and one unpaired electron. Like the carbocation, the carbon atom in a free radical typically undergoes sp² hybridization. The three regions of electron density (two bonds and one unpaired electron) form a trigonal planar structure with 120-degree bond angles. The unpaired electron occupies one of the p orbitals, and this orbital is involved in the radical’s reactivity.
Conclusion:
- Carbocation: sp² hybridization (trigonal planar geometry).
- Carbanion: sp³ hybridization (tetrahedral geometry).
- Free Radical: sp² hybridization (trigonal planar geometry).
