How does electron delocalization affect the electronic energy? A survey of neutral poly-nitrogen clusters

The relationship between the electron delocalization and the total electronic energy of a number of neutral poly-nitrogen clusters are studied at B3LYP/aug-cc-pVDZ computational level. It is shown that increasing the electron delocalization is accompanied with decrease of the total electronic energy. However, the geometry of clusters affects the amount of energy decrease. The energy decrease in more prominent in planar and linear clusters compared with the three dimensional, cage like, clusters with the same degree of the electron delocalization. Aromaticity of clusters whose relative electron delocalizations are higher/lower than other clusters is studied by means of the Nucleus Independent Chemical Shift (NICS). It is shown that predicted aromaticity trend based on electron delocalization in these species is in line with that emerged from NICS study, i.e. magnetic aromaticity.