| The structural stability of a chosen set of important organoazides was investigated using ab initio calculations. The 6-311++G** extended basis set at the DFT-B3LYP level was employed in most of the work. Full energy optimization was performed at the ground states as well as the transition states for the systems under the study. It was found that when the conjugation effect in halocarbonylazides, halovinylazides, dihalovinylazides, nitrosoazide, nitroazide and halosulfonylazideis dominated, these systems exist as a mixture of cis and trans conformation, except the halosulfonylazides in which there was a single minimum and that is the gauche conformation. The most probable resonance structure for the azide group was proposed based in the calculated azide group bond lengths and the values of the rotational barrier for the torsional angle. Complete normal coordinate analyses were performed to derive the potential energy distribution (PED) for each stable conformation in the molecular systems. The calculated vibrational spectra for each system were plotted and reliable assignments of the vibrational wavenumbers were made based on the vibrational frequencies, calculated PED values, Raman activities, IR intensities, depolarization ratios as well as the observed frequencies of similar molecules. |
