High-Level Systematic ab Initio Comparison of Carbon- and Silicon-Centered SN2 Reactions Attila Á. Dékány, Gyula Z. Kovács, and Gábor Czakó* MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary * E-mail: gczako@chem.u-szeged.hu 2 HF H 0.0000000000 0.0000000000 -0.8713729581 F 0.0000000000 0.0000000000 0.0462297625 2 HCl H 0.0000000000 0.0000000000 -1.2414625727 Cl 0.0000000000 0.0000000000 0.0352951735 2 HBr H 0.0000000000 0.0000000000 -1.4017183090 Br 0.0000000000 0.0000000000 0.0176818176 2 HI H 0.0000000000 0.0000000000 -1.6036869021 I 0.0000000000 0.0000000000 0.0127372056