Aromaticity of Substituted Benzene Derivatives Employing a New Set of Aromaticity Descriptors Based on the Partition of Electron Density

Aromatic compounds represent about two‐thirds of known molecules. Despite that, aromaticity still lacks a precise definition, leading to the use of various descriptors to quantify it. In this work, we employ a new set of six descriptors (ACS Omega 2025, 10 , 14157) built from components of the quadrupole moment tensor from the Stone's Distributed Multipole Analysis (DMA) to examine the aromaticity trends in monosubstituted benzene derivatives (, , , , , , , , and ) and para ‐homodisubstituted analogs (, , , , , and ). The tensor is the first term in the DMA electric multipole expansion to include out‐of‐plane electron density contributions. Using a machine learning clustering technique, we identified four groups of molecules: neutral with minimal variation, neutral with strong perturbation ( and ), positively, and negatively charged species. Comparisons with the traditional aromaticity descriptors , , , , , and were carried out. Among the ‐based descriptors, , which is computed 1 Å above the ring plane, exhibited the highest correlation with those descriptors, though small (). All the ‐based descriptors reproduced the same trends of the traditional indices, except for the negative substituents, which were only correctly described by the former ones. We found that ‐based descriptors correlated with ionization potentials (), electron affinities (), electronegativities (), electrophilicity indexes (), and electron‐donating/accepting power (, ), but not with the chemical hardness (). In contrast, , , , and correlated only with , while and showed no correlation. Therefore, our results show that the ‐based descriptors reflect the π‐electron delocalization characteristic of aromaticity and also can describe frontier‐orbital reactivity trends.