# Explanation of SN2 Mechanism using MOT

SN2 is usually explained by MOT, where we state that the incoming nucleophile starts donating the electron density into the σ∗ orbital and the carbon-leaving group bond weakens and finally breaks and a sigma bond is formed between the nucleophile and the carbon atom.

My question is that is a sigma bond is being formed between carbon atom and the nucleophile, which orbital is being used for that? According to me, it should be σ Bonding orbital because only then the bond formed would be stable. But the fact that the nucleophile donated density into σ∗ and the orbital being used for bond formation is σ seems weird to me.

Note- There is a similar question regarding MOT and SN2, but it does not answer my query Clarification on the $\mathrm{S_N2}$ mechanism