Hydrogen Bonding and Proton Transfers Involving the Carboxylate Group
Journal of the American Chemical Society
American Chemical Society
The complex formed between HCOO- and HOH is examined by ab initio methods using a 4-31+G* basis set. A number of minima are located in the potential energy surface, the most stable of which is of C2, geometry wherein both protons of HOH participate in H bonds. The barrier impeding proton transfer between OH- and HCOO- rises with increasing intermolecular separation for each of the arrangements studied. As the OH- anion moves toward the C-0 axis of HCOO-, the equilibrium position of the bridging proton is shifted toward the former group, paralleling earlier observations for the pair of neutral subunits HCOOH and HOH. On the other hand, HCOO- and HCOOH behave in different fashion with respect to motions of the hydroxyl group out of the carboxyl plane. These patterns are explained simply on the basis of differing ion-dipole interactions, as are small differences in the optimal geometries and proton-transfer behavior of the various arrangements of the two subunits.
Hydrogen Bonding and Proton Transfers Involving the Carboxylate Group S. M. Cybulski and S. Scheiner J. Am. Chem. Soc., 1989 111 (1), 23-31.