Calculations of current densities for neutral and doubly charged persubstituted benzenes using effective core potentials

Magnetically induced current density susceptibilities and ring-current strengths have been calculated for neutral and doubly charged persubstituted benzenes C₆X₆ and C₆X₆ ²⁺ with X = F, Cl, Br, I, At, SeH, SeMe, TeH, TeMe, and SbH₂. The current densities have been calculated using the gauge-including magnetically induced current (GIMIC) method, which has been interfaced to the Gaussian electronic structure code rendering current density calculations using effective core potentials (ECP) feasible. Relativistic effects on the ring-current strengths have been assessed by employing ECP calculations of the current densities. Comparison of the ring-current strengths obtained in calculations on C₆At₆ and C₆At₆ ²⁺ using relativistic and non-relativistic ECPs show that scalar relativistic effects have only a small influence on the ring-current strengths. Comparisons of the ring-current strengths and ring-current profiles show that the C₆I₆ ²⁺, C₆At₆ ²⁺, C₆(SeH)₆ ²⁺, C₆(SeMe)₆ ²⁺, C₆(TeH)₆ ²⁺, C₆(TeMe)₆ ²⁺, and C₆(SbH₂)₆ ²⁺ dications are doubly aromatic sustaining spatially separated ring currents in the carbon ring and in the exterior of the molecule. The C₆I₆ ⁺ radical cation is also found to be doubly aromatic with a weaker ring current than obtained for the dication.