Ring currents and magnetic properties of C48N12 dodecaaza[60-S6]fullerenes

The continuous transformation of the origin of the current density (CTOCD) method has been employed, at the ab initio CHF level of theory and adopting a medium size ad hoc polarized basis set, to predict fairly accurate, origin-independent magnetic properties for the two dodecaaza[60-S-6]fullerene isomers. The results show that the two isomers have a very different magnetic behavior, the thermodynamically less stable isomer (I) being characterized by paratropic pi-electron ring currents, which largely reduce the overall molecular diamagnetism, and, on the contrary, the more stable isomer (II) characterized by diatropic pi-electron ring currents flowing on the external hexagons of each triphenylene-type unit. However, on the basis of the computed magnetizability and central magnetic shielding, II is found to be no more aromatic than fullerene C-60. Computed C-13 and N-15 magnetic shieldings of both isomers are reported, which might be useful for identification purposes.