A new approach for aromaticity criterion based on electrostatic field gradient.

In this research, electric field gradient (EFG), which is the first derivative of electric field, is applied for evaluation of aromaticity of 89 cyclic organic compounds. In our calculations, DFT procedure (b3lyp) with basis set 6-311++G has been employed, and the obtained electronic structures and frequency test has been done for optimized geometries. The aromaticity evaluated for these compounds by EFG procedure is successfully compared with other well-known indices in literature, especially with nuclear independent chemical shift (NICS). These comparisons show that EFG method of assessment of aromaticity can be used as a rather valid procedure for this purpose. Flexibility and simplicity of EFG make this method a rather easy procedure for assessment of aromaticity. Since EFG method of aromaticity evaluation does not need specific programming and it can be done by known software such as Gaussian, therefore, the availability for everyone to calculate desired aromaticity by this method is one of attractive feature of it similar to NICS.