Efficiency of the NICSzz-scan curves to probe the antiaromaticity of organic and inorganic rings/cages.
In the present study it was demonstrated that the NICS(zz)-scan patterns along with symmetry-based selection rules can unequivocally probe the antiaromaticity in a wide range of antiaromatic organic and inorganic rings/cages. The NICS(zz)-scan profiles typical of antiaromaticity correspond to symmetric curves around the axis perpendicular to the ring plane with the positive NICS(zz)(R) values decaying rapidly and monotonically with respect to the distance R from the ring center. The magnitude of the induced paratropic ring currents is determined by the magnitude of the excitation energies of the rotationally (R(z)) allowed HOMO --> LUMO transitions. The appearance of the NICS(zz)-scan curves in conjunction with the symmetry-based selection rules constitute a powerful magnetic criterion of antiaromaticity capable of predicting the antiaromaticity in the realm of antiaromatic organic, inorganic and "all-metal" molecules lifting up all controversies with respect to the aromaticity/antiaromaticity for some peculiar aromatic/antiaromatic molecules.
Tsipis
Athanassios C
AC
Laboratory of Inorganic and General Chemistry, Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece. attsipis@cc.uoi.gr