Interplay of para- and diatropic ring currents [(anti)aromaticity] of macrocyclic rings subject to conformational influences, further annelation and hydrogenation of aromatic ring moieties

Abstract

The spatial magnetic properties (Through Space NMR Shieldings—TSNMRS) of a variety of porphyrins, hemiporphyrazines and tetraoxo[8]circulenes have been computed, visualized as Iso-chemical Shielding Surfaces (ICSS) of various size and direction, and were examined subject to the interplay of present (para)-diatropic ring currents [(anti)aromaticity] and influences on the latter property originating from the macrocyclic ring conformation, further annelation and partial to complete hydrogenation of aromatic ring moieties. Caution seems to be indicated when concluding from a single NICS parameter to present (para)diatropic ring currents [(anti)aromaticity].