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EnglishWe have quantum chemically explored the mechanism of the substitution reaction between CH3X− and the homo- and heterodichalcogenides CH3X′X″CH3 (X, X′, X″ = S, Se, Te) using relativistic density functional theory at ZORA-OLYP/TZ2P and COSMO for simulating the effect of aqueous solvation. In the gas phase, all substitution reactions proceed via a triple-well addition−elimination mechanism that involves a stable three-center intermediate. Aqueous solvation, in some cases, switches the character of the mechanism to double-well SN2 in which the stable three-center intermediate has become a labile transition state. We rationalize reactivity trends and some puzzling aspects of these elementary reactions, in particular, vanishing activation energies and ghost three-center intermediates, using the activation strain model (ASM).
| Titolo: | Addition−Elimination or Nucleophilic Substitution? Understanding the Energy Profiles for the Reaction of Chalcogenolates with Dichalcogenides | |
| Autori: | ||
| Data di pubblicazione: | 2016 | |
| Rivista: | ||
| Abstract: | We have quantum chemically explored the mechanism of the substitution reaction between CH3X− and the homo- and heterodichalcogenides CH3X′X″CH3 (X, X′, X″ = S, Se, Te) using relativistic density functional theory at ZORA-OLYP/TZ2P and COSMO for simulating the effect of aqueous solvation. In the gas phase, all substitution reactions proceed via a triple-well addition−elimination mechanism that involves a stable three-center intermediate. Aqueous solvation, in some cases, switches the character of the mechanism to double-well SN2 in which the stable three-center intermediate has become a labile transition state. We rationalize reactivity trends and some puzzling aspects of these elementary reactions, in particular, vanishing activation energies and ghost three-center intermediates, using the activation strain model (ASM). | |
| Handle: | http://hdl.handle.net/11577/3195797 | |
| Appare nelle tipologie: | 01.01 - Articolo in rivista |
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