Neue Klasse: Erstmals konnten Strukturen von aus Thuiaria breitfussi isolierten Verbindungen – den Breitfussinen – aufgeklärt werden. Diese Strukturklasse besteht aus Indol‐Oxazol‐Pyrrol‐Einheiten. Wegen der geringen Mengen gelang keine Kristallisation, weshalb die Strukturen mit einer neuartigen Kombination aus Rasterkraftmikroskopie (AFM) und Dichtefunktionalrechnungen bestimmt wurden. Mit AFM ließen sich alle Verknüpfungspunkte der Ringe und der anderen Substituenten festlegen.
We demonstrate that the apparent disagreement between experimental determinations and four-component relativistic calculations of the absolute shielding constants of heavy nuclei is due to the breakdown of the commonly assumed relation between the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the NMR shielding constants. We demonstrate that this breakdown has significant consequences for the absolute shielding constant of (119)Sn, leading to errors of about 1000 ppm. As a consequence, we expect that many absolute shielding constants of heavy nuclei will be in need of revision.
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