Which type of reaction typically results in an inversion of configuration?

In an SN2 reaction, the mechanism involves a direct backside attack by the nucleophile on the electrophile, typically a carbon atom that is attached to a leaving group. This backside attack occurs simultaneously with the departure of the leaving group, resulting in a transition state where the nucleophile and the leaving group are both partially bonded to the carbon.

As the nucleophile approaches from the opposite side of the leaving group, this results in the inversion of configuration at the carbon center. If the carbon is a stereocenter (like a chiral carbon), the result of this reaction is that the stereochemistry is inverted. For example, if the starting material is in the R configuration due to its three substituents, the product will have an S configuration.

This inversion of configuration is a hallmark of SN2 mechanisms and is crucial to understanding stereochemical outcomes in various reaction scenarios.