Chemistry - Halogen Derivative Question with Solution | TestHub

The ${\text{S}}_{\text{N}}2$ mechanism is a concerted, single-step process where the nucleophile attacks the electrophilic carbon from the side opposite to the leaving group.

During this process, a transition state is formed in which the central carbon atom is partially bonded to five groups (the incoming nucleophile, the leaving group, and three other substituents), making it penta-coordinated.

There is no carbocation intermediate formed in the ${\text{S}}_{\text{N}}2$ mechanism, which rules out the formation of a planar ${\text{sp}}^2$ hybridized carbocation.

The reaction proceeds with complete inversion of configuration (Walden inversion), not racemization.

Answer: The ${\text{SN}}^2$ mechanism includes a transition state with penta coordinating carbon.