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Article
Effect of Bond Multiplicity upon Hydrogen Bonding and Proton Transfers. Double Bonded Atoms
Journal of the American Chemical Society (1992)
  • Steve Scheiner, Utah State University
  • Lan Wang
Abstract

Ab initio methods are used to study the interactions between H2C=CH2 and H2C=NH and their deprotonated anions. (H2CCH-H-CHCH2)- is the most weakly bound with a complexation energy of 5.6 kcal/mol at the correlated MP2 level as compared to the stronger interaction of 10.3 for (HNCH-H-CHNH)- where the peripheral C atom has been replaced by N. The strongest interaction of 15.4 kcal/mol is observed in (H2CN-H-NCH2)- where N atoms participate directly in the H-bond. (H2CCH-H-CHCH2)- contains the longest intermolecular separation while the N-N distance in the latter complex is the shortest. This separation between subunits undergoes a contraction between 0.5 and 0.9 A as the proton reaches the transfer midpoint. The highest proton transfer barrier of 13 kcal/mol is observed for (H2CCH-H-CHCH2)-. In contrast, the small barrier in (H2CN-H.-NCH2)- is eliminated altogether when zero-point vibrations are considered. Transfer rates are computed using modified RRKM theory. These results are placed within the broader context of other complexes in which the atoms participating in the H-bond are single- and triple-bonded within their respective subunits so as to arrive at systematic conclusions regarding the effects of such multiple bonding upon the energetics of H-bond formation and proton transfer.

Keywords
  • effect,
  • bond,
  • multiplicity,
  • hydrogen bonding,
  • proton,
  • transfers,
  • double,
  • bonded,
  • atoms
Disciplines
Publication Date
May 1, 1992
Publisher Statement
Originally published in the Journal of the American Chemical Society by the American Chemical Society . Publisher’s PDF available through remote link. DOI: 10.1021/ja00036a012
Citation Information
Effect of Bond Multiplicity upon Hydrogen Bonding and Proton Transfers. Double Bonded Atoms S. Scheiner, L. Wang J. Am. Chem. Soc. 1992 114 (10), 3650-3655.