Ab initio study of azolides:: Energetic and spectroscopic properties

We report the ab initio study of twenty-four azolides derived from pyrrole, imidazole, pyrazole, both triazoles, tetrazole, pentazole, indole and carbazole bearing at the nitrogen atom the groups COMe, CHO, COCF3 and CO2Me. Theoretical values (isomerism, barriers, dipole moments, C=O stretching) are compared with experimental ones, when available, and also internally compared. A special effort has been devoted to the calculation of the absolute shieldings for the different nuclei present in azolides. At the level of calculation used (RHF/6-311G**) the results are satisfactory. To complete the nmr data from the literature, some H-1, C-13, N-15, O-17 and F-19 chemical shifts have been determined.