Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The comparison of <jats:italic>D</jats:italic> index with HOMHED gave a good correlation (R<jats:sup>2</jats:sup>= 0.8221). However, a modification of <jats:italic>D</jats:italic> index, namely <jats:italic>D’</jats:italic>, where the number of cycles involved in the tested molecule is substituted by the ratio between the number of atoms involved in π orbitals in the tested molecule and in reference molecule, gave a better correlation with a larger number of compounds (R<jats:sup>2</jats:sup>=0.8819), The correlation of <jats:italic>D’</jats:italic> with calculated HOMHED for pentatomic heterocyclic compounds did not give a unique correlation but a series of possible correlations. This behavior depends on the parameters used for the calculation of HOMHED that allow some negative values. In fact, the comparison of <jats:italic>D’</jats:italic> with NICS for selected pentatomic heterocycles gave good correlation. Good correlations were observed also in the comparison of <jats:italic>D’</jats:italic> with HOMHED and NICS for antiaromatic compounds.</jats:p>