Vibrational spectra of H5O2+ ion in crystalline YH5O2(C2O4)2 · H2 O

Polarized Raman and infrared spectra of crystalline YH5O2(C2O4)2 · H2O and its deuterated analogs were measured over the frequency interval from 20 to 4000 cm−1. Primary consideration was given to recording the vibrational spectrum of the diaquated hydrogen ion, H5O2+, and to correlating the spectral properties of this species with the results from recent neutron diffraction studies of yttrium oxalate trihydrate. Calculations based on models of H5O2+ produced root-mean-square displacements of the central proton which were compared with the thermal parameters derived from neutron diffraction data. A comparison of calculated and observed properties suggested that H5O2+ may be represented by a model based on a proton trapped between two water molecules.