The ground and excited state hydrogen transfer potential energy surface in 7-azaindole

Multireference wave functions, augmented by second-order perturbation theory, are used to examine the hydrogen transfer process in the ground and first excited states of 7-azaindole and in the 1:1 7-azaindole: water complex. The presence of one water molecule dramatically reduces the barrier to proton transfer in both electronic states. In the excited state the order of the two tautomers is reversed, and the barrier for the hydrogen transfer from the (now higher energy) normal structure to the tautomer in the presence of one water is estimated to be less than or equal to 6 kcal/mol.