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

Abstract

Magnetically induced current density susceptibilities and ring-current strengths have been calculated for neutral and doubly charged persubstituted benzenes CX and CX with X = F, Cl, Br, I, At, SeH, SeMe, TeH, TeMe, and SbH. 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 CAt and CAt 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 CI, CAt, C(SeH), C(SeMe), C(TeH), C(TeMe), and C(SbH) dications are doubly aromatic sustaining spatially separated ring currents in the carbon ring and in the exterior of the molecule. The CI radical cation is also found to be doubly aromatic with a weaker ring current than obtained for the dication.

Aromaticity of some carbenes and their heavier analogs in light of gauge‐including magnetically induced current approach as a new magnetic criterium

“…Hydrogen atoms or methyl groups were chosen as substituents R. It is noteworthy that the nature of R (even if this is such a donor group as tBu) barely influences the results. All computations including those of shielding matrices were performed using Gaussian09 program package with an interface for GIMIC . The typical Gaussian input contained an entry RB3LYP/Def2‐TZVP NMR = GIAO NoSymm Int (Grid = Ultrafine, NoBasisTransform).…”

“…All computations including those of shielding matrices were performed using Gaussian09 program package [22] with an interface for GIMIC. [23] The typical Gaussian input contained an entry RB3LYP/Def2-TZVP NMR = GIAO NoSymm Int (Grid = Ultrafine, NoBasisTransform). The values of ring current strength obtained in this way for model molecules C 6 H 6 (11.8), C 4 H 4 (−19.9), C 3 H 4 (6.7), C 3 H 6 (10.0) nearly coincide with the previously published data.…”

Evaluation of Aromaticity for Open‐Shell Singlet Dicyclopenta‐Fused Acenes and Polyacenes Based on a Magnetically Induced Current

“…The MIC density ( (r)) was calculated using the GIMIC method from the unperturbed and the magnetically perturbed electron densities. For open‐shell systems, NMR shielding calculations yield unperturbed and magnetically perturbed density matrices for α and β electrons.…”

“…The GIMIC program is independent of the quantum chemistry calculation package but it requires input data in the required format. In this study, the GIMIC interface with Gaussian 09 (Gaussian2gimic.py) was used, for which the calculation of NMR properties is available at the DFT level for open‐shell systems (see the Supporting Information). The external magnetic field was applied perpendicular to the molecular plane of DPAs and PAs ( z direction).…”

“…In this expression, r = (x, y, z)i sapositioni n space, (i, j, k)i saset of (x, y, z), J B j ;s i r ðÞis the ith component of the MIC density vector, B j is the externalm agnetic field applied in the j Cartesiand irection, u(r)i savectorc ontaining the GIAO basis functions for grid point r, [34][35][36] the D s sa re the atomico rbital density matrices for s = a and b spin,a nd e ijk is the Levi-Civita tensor.T he GIMIC program is independent of the quantum chemistry calculation package but it requires input data in the required format. In this study,t he GIMIC interface with Gaussian09( Gaussian2gimic.py) was used, [33,37] for which the calculation of NMR properties is availablea tt he DFT level for open-shell systems( see the Supporting Information). The external magneticfield was appliedp erpendicular to the molecular plane of DPAs and PAs( z direction).…”