Probing the reactivity of microhydrated α‐nucleophile in the anionic gas‐phase SN2 reaction |
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| Authors: | Wen‐Yang Zhao Jie Yu Si‐Jia Ren Xi‐Guang Wei Fang‐Zhou Qiu Peng‐Hui Li He Li Yi‐Peng Zhou Chang‐Zhen Yin An‐Pu Chen Hao Li Lei Zhang Jun Zhu Yi Ren Kai‐Chung Lau |
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| Affiliation: | 1. College of Chemistry and Key State Laboratory of Biotherapy, Sichuan University, Chengdu, China;2. West China School of Medicine, Sichuan University, Chengdu, China;3. Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong;4. State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, Xiamen University, Xiamen, China |
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| Abstract: | To probe the kinetic performance of microsolvated α‐nucleophile, the G2(+)M calculations were carried out for the gas‐phase SN2 reactions of monohydrated and dihydrated α‐oxy‐nucleophiles XO?(H2O)n = 1,2 (X = HO, CH3O, F, Cl, Br), and α‐sulfur‐nucleophile, HSS?(H2O)n = 1,2, toward CH3Cl. We compared the reactivities of hydrated α‐nucleophiles to those of hydrated normal nucleophiles. Our calculations show that the α‐effect of monohydrated and dihydrated α‐oxy‐nucleophiles will become weaker than those of unhydrated ones if we apply a plot of activation barrier as a function of anion basicity. Whereas the enhanced reactivity of monohydrated and dihydrated ROO? (R = H, Me) could be observed if compared them with the specific normal nucleophiles, RO? (R = H, Me). This phenomena can not be seen in the comparisons of XO?(H2O)n = 1,2 (X = F, Cl, Br) with ClC2H4O?(H2O)n = 1,2, a normal nucleophile with similar gas basicity to XO?(H2O)n = 1,2. These results have been carefully analyzed by natural bond orbital theory and activation strain model. Meanwhile, the relationships between activation barriers with reaction energies and the ionization energies of α‐nucleophile are also discussed. © 2015 Wiley Periodicals, Inc. |
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| Keywords: | gas‐phase SN2 reaction microhydrated nucleophile alpha‐effect gas basicity activation strain model |
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