Scalar and Spin-Orbit Relativistic Corrections to the NICS and the Induced Magnetic Field: The case of the E122- Spherenes (E = Ge, Sn, Pb)

Can relativistic effects modify the NICS and the B-ind values? In this manuscript we evaluate the relativistic corrections incorporated via the zeroth-order regular approximation to the calculations of nucleus-independent chemical shifts and the induced magnetic field (B-ind) in the E-12(2-) spherenes (E = Ge, Sn, Pb). We found that both electron delocalization descriptors are strongly affected by the relativistic corrections. For instance, for plumbaspherene, the difference in values from the nonrelativistic to the relativity-included calculation is almost 40 ppm! Our results show that the changes observed in the NICS and B-ind values in the title cages are a consequence of the treatment of the relativistic effects. If these effects are included as scalar or spin orbit calculations, then we can establish the next trend: Ge-12(2-) is a nonaromatic species, Sn-12(2-) is a low aromatic species, and Pb-12(2-) is strongly aromatic, according to calculated NICS and B-ind values. Thus, any prediction of electron delocalization in molecules containing heavy elements without considering an adequate treatment for relativistic effects may lead to an erroneous chemical interpretation.