Document Type : Regular Article
Department of Chemistry, Zanjan Branch, Islamic Azad University, Zanjan, Iran
Department of Nanochemistry, Faculty of Pharmaceutical Chemistry, Pharmaceutical Sciences Branch, Islamic Azad University ,Tehran - Iran (IAUPS )
In this research, we report the results of DFT calculations using xc-hybrid functional, B3LYP and employ NBO interpretation to investigate the stereoelectronic effects. Electrostatic and steric impacts on the conformational properties of 1,2-difluorodiazene (1), 1,2-dichlorodiazene (2) and 1,2-dibromodiazene (3) are also studied. Factors determining the thermodynamically stable molecular structure of 1,2-dihalodiazenes and their analogues containing P and As atom are discussed, and the energetic effects of intra-molecular hyperconjugations and steric repulsion in each molecular system are theoretically estimated using NBO theory. The Energy components calculated help us to justify the conformational behaviour of our target compounds. One of the interesting features extracted from NBO analysis is that dissociation energies are controlled by the stabilization energies associated with electron delocalizations in these compounds. The main parameter considered in this study is the Gibbs free energy estimated for cis and trans configurations of compounds and for the cis-to-trans conversion through rotation and inversion mechanisms.