Water-anion vibrational coupling in some crystallohydrates

In treating the vibrational spectra of crystallohydrates, it is usually assumed that the water molecules vibrate independently (or nearly so) from the rest of the structural units and, consequently, the bands which shift on deuteration are automatically assigned to water modes (internal or external). In a number of hydrates of metal carboxylates, however, we were able to detect indications of water-anion vibrational coupling.