Vibrational spectroscopic study of pyrrole and its deuterated derivatives: comparison of the quality of the applicability of the DFT/Becke3P86 and the DFT/Becke3LYP functionals

The aim of our work is a reassignment of the vibrational spectra of pyrrole based on high-level quantum-chemical calculations. This is a continuation of our earlier works on one side of pyrrolydine and N-methylpyrrolidine and on the other side of five-membered ring parent molecules with two-ring nitrogens. Infrared and Raman spectra are reported for the isotopic species of pyrrole, 1-deuteropyrrole and penradeuteropyrrole. The molecular structure and the harmonic force field were calculated applying the ab initio density functional theory (DFT) level with both the Becke3P86 and the Becke3LYP functionals with the 6-311G(d,p) basis set. The force fields were fitted to the experimental fundamentals using in both cases eight scale factors. Though some scaled frequencies show larger deviations from the experimental ones, the percentage deviations of the calculated frequencies from the experimental ones are less than 1.0% for pyrrole and less than 1.2% for the deuterated derivatives in the case of both applied functionals. (C) 2000 Elsevier Science B.V. All rights reserved.