Proton transfers along the hydrogen bonds in the systems (H3NHNH3)+ and (H20HOH2)+ are studied by ab initio molecular-orbital methods. The 4-31G basis set is used within the Hartree-Fock formalism to calculate transfer potentials for conformations of each system involving linear and angular deformations of the hydrogen bond. Potentials obtained by using the rigid-molecule approximation are in excellent agreement with those calculated including full geometry optimizations at each stage of transfer. Transfer energy barriers for (NzH7)+ are found to vary with bond distortion in the same qualitative fashion as for the isoelectronic (02H5)+, although barriers in the former system are systematically lower. Certain calculated electronic properties of both (N2H7)+ and (02H5)+ are shown to correlate very well with the transfer energy barriers. Electron density rearrangements which accompany the transfer of the proton are examined in some detail by population analyses and by electron density difference maps to determine basic similarities characteristic of proton transfers as well as fundamental differences between the (NzH7)+ and (OzH6)+ systems.
Proton Transfers in Hydrogen Bonded Systems. 4. Cationic Dimers of NH3 and OH2Journal of Physical Chemistry
PublisherAmerican Chemical Society
Citation InformationProton Transfers in Hydrogen Bonded Systems. 4. Cationic Dimers of NH3 and OH2 S. Scheiner J. Phys. Chem., 1982 86 (3), 376-382.