Fig. 4. NICSzz isosurfaces for
BxNx clusters (x = 3 – 11) at +/- 4 ppm
isovalue. Blue color represents negative (diatropic) values and red
color represent positive (paratropic) values.
In order to gain more insights about the (anti)aromaticity patterns in
“problematic” B2N2 and
B5N5, dissected NICSzzisolines have been obtained which allows us to observe in detail the
contributions of the core, σ and π electrons, results are shown in Fig.
5. In the case of B2N2, core electron
contributions to NICSzz present small diatropic
short-range values. Surprisingly, σ-electron contributions present
unexpected paratropic long-range pattern which resembles antiaromatic
compounds, whereas π-electron contributions shows to an antiaromatic
pattern, concluding that this cluster is doubly antiaromatic.