FOURIER-TRANSFORM RAMAN-SPECTRUM OF POLYCRYSTALLINE PYRAZOLE, VIBRATIONAL ASSIGNMENT AND ABINITIO CALCULATIONS

The Fourier transform Raman spectrum from 100 to 3300 cm-1 of liquid and polycrystalline pyrazole, NHN=CHCH=CH, was recorded. The frequencies for several of the fundamentals are significantly different from those obtained from the Raman spectra of solutions. The data are interpreted in detail. The previous assignment of one of the out-of-plane fundamentals (A") for the isolated molecule is questioned. The structural parameters, fundamental vibrational frequencies and values for the force constant were obtained from ah initio Hartree-Fock gradient calculations utilizing the 3-21G basis set. These results are compared with the values of some of these physical quantities previously reported.