Relativity or aromaticity? A first-principles perspective of chemical shifts in osmabenzene and osmapentalene derivatives

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Publikace nespadá pod Ekonomicko-správní fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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FOROUTANNEJAD Cina VÍCHA Jan GHOSH Abhik

Rok publikování 2020
Druh Článek v odborném periodiku
Časopis / Zdroj Physical Chemistry Chemical Physics
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
www https://doi.org/10.1039/D0CP01481H
Doi http://dx.doi.org/10.1039/d0cp01481h
Klíčová slova zeta basis set; triple-zeta; electrons delocalized; heavy-atoms; metallabenzenes; anisotropy
Popis We have studied the magnetic response properties and aromaticity of osmium metallacycles by means of scalar-relativistic (1c) and fully relativistic (4c) density functional theory computations. For osmabenzene, whose aromatic character is controversial, a topological analysis of the current density has revealed the presence of a unique sigma-type Craig-Mobius magnetic aromaticity. We show that the partially filled osmium valence shell induces a large paratropic current, which may interfere with certain methods commonly used to analyze aromaticity, in particular NICS. Further, we show that the extreme deshielding of the light atoms in the vicinity of the osmium atoms in osmapentalene derivatives is not a consequence of aromaticity but can be explained by paramagnetic couplings between sigma(Os-C) bonding orbitals and the pi*(Os) orbitals. We demonstrate that variations in the orientation of the induced magnetic currents through the molecule dictates the alternating signs of the spin-orbit contribution to the NMR chemical shift.
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