Abstract For some gas-phase X- + CH3Y → XCH3 + Y- SN2 nucleophilic substitution reactions a pre-reaction complex is formed in which the attacking anion binds to a H-atom to form X-⋯HCH2Y. In this work properties of this complex are investigated, for the OH- + CH3I and F- + CH3I reactions, to determine whether the HO-⋯HCH2I and F-⋯HCH2I complexes should be considered hydrogen-bonded complexes. Properties considered for these complexes are their structures, vibrational frequencies, well depths, and partial atomic charges. Also considered is the role of the HO-⋯HCH2I complex in proton transfer for both the proton transfer and SN2 reaction pathways. The results of these analyses indicate that these X-⋯HCH2Y complexes are hydrogen bonding complexes.
Bibliographical noteFunding Information:
This material is based upon work supported by the Robert A. Welch Foundation under grant D-0005 . Support was also provided by the High-Performance Computing Center (HPCC) at Texas Tech University (TTU), under the direction of Philip W. Smith, and the TTU Department of Chemistry & Biochemistry cluster Robinson, whose purchase was funded by the National Science Foundation under the CRIF-MU Grant No. CHE-0840493 . J. Zhang thanks the Fundamental Research Funds for the Central Universities, China (AUGA5710012114). The authors wish to acknowledge important discussions with Veronica Bierbaum and Casey Hynes.
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- Hydrogen bond
- Mulliken charge
- Pre-reaction complex