WHAT GOVERNS THE STEREOCHEMISTRY OF THE S(N)2' REACTION

Ab initio calculations of negatively charged symmetrical and a unsymme trical transition states of the S(N)2' reaction indicate that due to e lectronic seasons and particularly Coulomb interactions the anti trans ition state is generally more stable than the syn transition state. Th e experimentally often observed syn preference results mainly from the interaction with a polar solvent and/or the gegenion, which gives ris e to higher stabilization of the syn transition state than of the anti transition state.