Background: Recently a new index, D, has been introduced to quantitatively describe the aromatic properties of an organic compound.
Methods: The D index was calcuted optimizing the structure of the selected compound and examining the energy of π orbitals.
Results: The index D shows to correlate with NICS of pentaatomic heterocyclic compounds. Several correlations were found depending on the nature, number and relative position of the heteroatoms. The same type of correlations were found by using ASE to correlate with NICS.
Conclusion: The D index confirms to be able to describe the aromatic character of pentaatomic aromatic compounds.
Keywords: Aromaticity, ASE, DFT, NICS, occupied π orbitals.