Stabilization of an excess electron on uracil by water. Ab initio study

Experiments performed on the uracil anion in the gaseous phase indicated that in this system the excess electron is dipole-bound. The experiments, however, also indicated that water solvation changes the character of the anion from dipole-bound to covalent. In this work we have used ab initio theoretical calculations to investigate the stabilization effect that the attachment of one or two water molecules has on the electron attached to uracil. The calculations concern both dipole-bound and covalently-bound electrons and reveal rich configurational isomerism of the complex of the uracil anion with H₂O molecules. The systems differ in terms of the structure of the solvation cluster formed around the excess electron.