Evaluation of NICSzz Isosurfaces
A three-dimensional analysis to assess the anisotropic effects of
NICSzz was carried out, providing more insights
regarding the (anti)aromaticity of the
BxNx clusters. NICSzzisosurfaces are depicted in Fig. 4. The presence of long-range diatropic
regions inside the rings are indicative of their aromatic character.
This can be observed in B3N3 where
diatropic zones are located at the center and, additionally, located in
nitrogen atoms due to the contributions of core electrons. The opposite
effect can be seen B2N2,
B4N4 and
B6N6, where strong paratropic long-range
zones are located at the center of these rings, denoting their
antiaromatic character. Along with this, the diatropic zones located in
the nitrogen atoms are also observed.
In B5N5, diatropic zones in nitrogen
atoms and above the molecular ring are observed, however it is possible
to see paratropic values at the centre of the ring, this characteristic
pattern has been observed in non-aromatic organic systems including
cyclopropane and cyclohexane58. The rest of the
systems present diatropic regions located in the nitrogen atoms and
short range paratropic zones in the center of the ring, characteristic
of its non-aromatic nature.