Spherical Aromaticity of Tetrahedral Pnictogens Through Off‐Nucleus Isotropic Magnetic Shielding

Abstract

This work revealed the spherical aromaticity of some inorganic E4 cages and their protonated E4H+ ions (E=N, P, As, Sb, and Bi). For this purpose, we employed several evaluations like (0D‐1D) nucleus independent chemical shift (NICS), multidimensional (2D‐3D) off‐nucleus isotropic shielding σiso(r), and natural bond orbital (NBO) analysis. The magnetic calculations involved gauge‐including atomic orbitals (GIAO) with two density functionals B3LYP and WB97XD, and basis sets of Jorge‐ATZP, 6‐311+G(d,p), and Lanl2DZp. The Jorge‐ATZP basis set showed the best consistency. Our findings disclosed non‐classical aromatic characters in the above molecules, which decreased from N to Bi cages. Also, the results showed more aromaticity in E4 than E4H+. The NBO analysis attributed the aromaticity in the above molecules to the residual density of the overlapping σ‐bonding orbitals. So, the aromaticity in these molecules is unlike the classical aromaticity that is associated with electron delocalization. Scanning 1D σiso(r) variation along E−E bonds indicated a lowering in the shielding trend from N to Bi cages. The 3D results showed a similar decrease in the relative volumetric diffusion of the magnetic activity, whereas the volumetric ratio of V1ppm/V2ppm is almost constant for all the E4 cages.

Predicting a New Δ‐Proton Sponge‐Base of 4,12‐Dihydrogen‐4,8,12‐triazatriangulene through Proton Affinity, Aromatic Stabilization Energy, and Aromatic Magnetism

“…The last has involved using off-nucleus magnetic shielding (σ zz (r) and σ iso (r)) and NICS-and NICS zz -Scan. These techniques, which showed promising performance in our previous works, [57][58] have also been employed to study protonation impacts on aromaticity, besides visualizing the aromatic stabilization for the first time, which adds a crucial advancement to the works that tried linking magnetism of aromatics with their aromatic stabilization. [33,38,[59][60][61][62][63][64]…”

Tubular Magnetic Shielding Scan (TMSS): A New Technique for Molecular Space Exploration. (i) The Case of Aromaticity of Benzene and [n]Paracyclophanes

“…Over the years, several variants of the NICS index have been developed, including NICS(0), , NICS(1), NICS zz (0), NICS zz (1), , and NICS-Scan. , In addition, two- and three-dimensional multipoint magnetic probes have been developed, which are useful for scanning and imaging the magnetic shielding in specified spaces surrounding various molecules, including both typical − and biochemical , ones. The ability to evaluate not only aromaticity but also other chemical aspects, such as bonding ,,, and electron excitation effects − on molecular properties, makes these methods valuable in various chemical fields.…”