Quantum chemical calculations at the MP2/[aug]-cc-pVDZ level were used to generate a two-dimensional potential energy surface for an unusual double proton transfer reaction in which the region around the transition state is characterized by a plateau of almost constant energy. A cut of the first electronically excited singlet state potential energy surface along the ground-state reaction path was computed using time-dependent density functional theory. In addition, solvent effects which lead to significant changes of the surface were studied using a self-consistent reaction field approach.