In SN₂ reaction, the carbon in the transition state is

In the bimolecular nucleophilic substitution (SN₂) reaction, the incoming nucleophile interacts with the alkyl halide, causing the C-X bond to break, and a new bond is formed between carbon and the attacking nucleophile. This reaction is a single step reaction where there is formation of a transition state. In that state, the carbon atom is Penta coordinated because it is simultaneously bonded to the incoming nucleophile and the outgoing leaving group.