Density functional theory study of intermolecular interactions of cyclic tetrazole dimers

In this study the density functional theory at B3LYP/6-31++G(d,p) level was employed to evaluate the hydrogen bonding between tetrazole dimers in the gas phase. Four cyclic dimers including one 1H-1H and three 2H-2H dimers were considered. The N...H-N hydrogen bonding which studied in the self assembled structures has been estimated from stabilization energies. The calculated hydrogen-bonding energies of various tetrazole dimers showed a cooperative interaction in the cyclic ones. It was found that 1H-1H dimers are more stable and introduction of an electron-releasing group (ERG) into the tetrazole rings resulted in the formation of more stable hydrogen bonding. Harmonic frequencies of monomers and dimers were calculated and it was found that change in the complexation vibrations is sensitive to the strength of the N…H-N hydrogen bondings. Natural population analysis was performed to predict electrostatic interactions in the cyclic H-bonded complexes.