Quantum mechanical calculations of electronic structure for some azo imidazole compounds

Abstract EN

In this research, quantum mechanics calculations and using a semi-empirical methods (Parameterization of MNDO model, PM3) involved the balanced geometry, for seven azo compounds (A, B, C, D, E, F, and G).

The geometric dimensions (bond lengths and angles), heats of formations (Hf, kcal.mol-1), dipole moments (μ in Debye), orbital energies (EHOMO, ELUMO), ionization energies (IP, eV), a measure of stationary, (kcal.mol-1) charge and the electron densities have been calculated.

As show through a results that the bond length of (C-X) when (X = CH3, NO2) greater than (C-H), and the bond length of (CNO2) greater than (C-CH3), and the bond length of (N7 = N8) had the highest value at the position of meta, and the lowest value at the position of ortho and para in the case of substitutes (-CH3) and (-NO2) respectively.

The calculation results showed that each of two compounds (D and F) has a lower value of heat of formation in case of substitutes (-CH3,-NO2), respectively, i.e., when the compensation at the position para and Meta, the molecule more stability.

In addition, it has been found there is compatibility between the results of heat of formation with the results of study the effect of substitutes on the stability.

They also showed that the results at the comparison between the nitrogen atoms (N7, N8, N10, N13) at both the cases of compensation (-CH3, -NO2), found that the nitrogen atom (N13) had a lower value of electron density (the highest value of the charge), In contrast, the nitrogen atom (N10) had the highest value of electron density (less the value of charge).

In addition, the calculation results indicate that the values of electron densities of the nitrogen atoms of the above-mentioned, is increased in compounds that have substitutes group (-CH3), compared with other compounds, with the exception of nitrogen atom (N10).