What Dictates the α‑Effect in Gas-Phase SN2 Reactions? A Density Functional Theory Study

The α-effect is an important concept in chemistry and biochemistry, namely that for a bimolecular nucleophilic substitution (S_N2) reaction, the nucleophilicity of an atom is increased if its adjacent (α) atom has a lone pair of electrons, lowering the reaction barrier height and increasing the reaction rate. However, exceptions exist, even for very similar structural motifs. We investigate what underlies the α-effect in gas-phase S_N2 reactions …