Vibrational spectroscopy of diazoles

In this work the authors deal with the vibrational spectroscopy of the two diazole parent compounds, i.e. that of imidazole and pyrazole and their N-deuterated derivatives. Infrared spectra of these compounds were recorded in solid state, Raman spectra were measured in condensed phase using both parallel and perpendicular polarization of fight. The vibrational fundamental frequencies were calculated applying the density functional theory with the Becke3P86 functional,and the 6-311G(d,p) basis set. The results of the calculations were applied to the assigmnent of the vibrational fundamentals and the measured fundamental frequencies were used to refine the vibrational force constants. The considerable association of the compounds shifted the fundamental frequencies of the isolated molecules. In contrary to this fact the relative mean deviations between the measured and calculated frequencies were smaller than 1% for every investigated molecule. (C) 1999 Elsevier Science B.V. All rights reserved.