The equation-of-motion method is used to map out one-dimensional potentials for proton-coupled electron transfer in the [pyridine center dot(H2O)(n)](-), n = 3, 4, clusters. In both cases there is an avoided crossing between valence-type pyridinyl center dot(OH-) (H2O)(n-1) and dipole-bound pyridine center dot(H2O)(n)(-) anion species. For the n = 3 cluster, the mixing is sufficiently strong that both limiting structures are predicted to be sampled in the vibrational zero-point level. (C) 2016 Elsevier B.V. All rights reserved.