Figure 1.
Qualitative representation of the stationary points of the different unimolecular isomerization steps of SO3 hydration. Water addition concerted with a single proton transfer in the presence of a single water molecule (n = 1), hydration concerted with water-mediated double proton transfer (n = 2), hydration concerted with water-mediated double proton transfer in the presence of a third microsolvating water molecule (n = 2 + 1), and hydration concerted with the sequence proton transfer/rotation of H3O+/proton transfer in the presence of a third stabilizing water molecule (n = 3).