Field effects on Dihydrogen Bonded Systems
To investigate the hydrogen transfer within a crystal by means of the crystal field, the effect of an external electric field over three different proton equilibrium systems has been studied with ab initio methods. The equilibria chosen were: (1) from neutral molecules dihydrogen bonded to cation/H2/anion complexes, (2) from neutral/H2/neutral complexes to charged molecules dihydrogen bonded and (3) from neutral and charged molecules dihydrogen bonded to charged/H2/neutral complexes. The electric field was applied along the molecular axis increasing from 0.00557 to 0.03342 au. At the theoretical level, it has been found that by applying an external field the transfer of H atoms between two heavy atoms is possible. Thus, a coordinated hydrogen molecule became a dihydrogen bond in the case of Li+⋯H-H⋯F−. Oppositely, a dihydrogen bonded complex became two molecules coordinated to molecular hydrogen in the case of the H3N+-H⋯H-BH3− system.