Calculations of Frequencies and Intensities of the Lattice Vibrations of Thiourea and Thiourea-d4

Frequencies of the lattice vibrations of the room-temperature modification of thiourea and deuterated thiourea have been calculated assuming a simple force field. The calculated frequencies are in good agreement with the observed frequencies in the Raman and far-infrared spectra. Approximate relative intensities of the lattice vibrations in both spectra have been calculated and used to check the assignments given by the frequency calculation. One of the intermolecular force constants, 0.173 mdyn/Å, seems to represent a fairly strong S···H–N hydrogen bond.