Relativity or aromaticity? A first-principles perspective of chemical shifts in osmabenzene and osmapentalene derivatives
| Autor: | Cina Foroutan-Nejad, Abhik Ghosh, Jan Vícha |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Physics
010304 chemical physics Chemical shift General Physics and Astronomy chemistry.chemical_element Aromaticity 010402 general chemistry 01 natural sciences 0104 chemical sciences 3. Good health Paramagnetism Atomic orbital chemistry Chemical physics 0103 physical sciences Physics::Atomic and Molecular Clusters Molecule Osmium Density functional theory Physical and Theoretical Chemistry Valence electron |
| Zdroj: | Physical Chemistry Chemical Physics. 22:10863-10869 |
| ISSN: | 1463-9084 1463-9076 |
| 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 σ-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 σOs—C bonding orbitals and the π*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. |
| Databáze: | OpenAIRE |
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