Volume 23, Issue 18 e202200285
Research Article

Microsolvated Ion-Molecule SN2 Reactions with Dual Nucleophiles Induced by Solvent Molecules

Xiangyu Wu

Xiangyu Wu

Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081 China

Contribution: Data curation (lead), Formal analysis (lead), Writing - original draft (equal)

Search for more papers by this author
Dr. Chongyang Zhao

Corresponding Author

Dr. Chongyang Zhao

Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081 China

Contribution: Data curation (supporting), Formal analysis (supporting), ​Investigation (supporting), Writing - original draft (equal)

Search for more papers by this author
Prof. Dr. Jing Xie

Corresponding Author

Prof. Dr. Jing Xie

Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081 China

Contribution: Conceptualization (lead), Resources (lead), Supervision (lead), Writing - review & editing (lead)

Search for more papers by this author
First published: 07 June 2022
Citations: 1

Graphical Abstract

Solvent molecules induce new nucleophile HO(HOOH)(H2O)n-1 when microhydrated nucleophile HOO(H2O)n react with methyl halides. Incremental hydration increases the barriers of both HOO−SN2 and HO−SN2 pathways and enlarges their barrier differences. The origin of this barrier change is unveiled.

Abstract

Singly-hydrated HOO anion was found to induce alternative nucleophile HO via proton transfer from water molecule when reacting with CH3Cl. To investigate the generality of this effect, the competition between the solvent-induced HO−SN2 pathway and the normal HOO−SN2 pathway is studied for the microsolvated HOO(H2O)n=1,2,3+CH3X (X=F, Cl, Br, I) reaction by quantum chemistry calculations. Incremental hydration increases the barrier heights of both pathways and enlarges the barrier difference between them, which favors the HOO−SN2 pathway. Interestingly, the barrier difference is insensitive to the leaving group. Calculations show that the water induced HO−SN2 pathway is highly suppressed when the degree of hydration increases beyond two. The differential barrier under incremental hydration can be explained by solvent molecules stabilizing the HOMO level of HO(HOOH)(H2O)n-1 nucleophile more than that of the HOO(H2O)n nucleophile. Comparison between the HO- and HOO-nucleophiles suggests that α-effect exists. Activation strain analysis attributes the barrier differences to stronger TS distortion of the HO−SN2 pathway than that of the HOO−SN2 pathway.

Conflict of interest

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available in the supplementary material of this article.