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Acetylene as Potential Hydrogen-Bond Proton Acceptor
Journal of Molecular Structure (2002)
  • Steve Scheiner, Utah State University
  • S. J. Grabowski

Ab initio calculations are used to assess the ability of the C-C triple bond in acetylene to act as proton acceptor to donor molecules HF, HCl, HCN and HCCH. The strength of the interaction energy varies from 3 kcal/mol for the strongest of these complexes FH⋯HCCH, to 1 kcal/mol for the weakest (HCCH)2. The X–H bond of all donors undergoes the elongation characteristic of H-bonds, along with the red shift of its stretching frequency. In addition, electron density is transferred from the proton-acceptor molecule to the donor, and the bridging H becomes more positive. However, the magnitudes of these density shifts are larger than might be expected from a conventional H-bond. Opposite to a H-bond, the proton-accepting C atom loses density. Decomposition of the total interaction energy indicates the dominant role played by Coulombic attraction, as in a H-bond, but the exchange repulsion, charge transfer, and polarization terms are disproportionately larger than is typically seen in true H-bonds.

  • acetylene,
  • potential,
  • hydrogen bond,
  • proton,
  • acceptor
Publication Date
January 1, 2002
Citation Information
Acetylene as Potential Hydrogen-Bond Proton Acceptor S. Scheiner, S. J. Grabowski J. Mol. Struct. 2002 615 209-218