Magnetic susceptibilities and resonance energies of annelated [14] - and [18] annulenes

Abstract

Calculations of magnetic susceptibilities and topological resonance energies of annelated [14] - and [18] annulenes are reported. For several compounds the magnetic susceptibilities are also measured. In these cases a good agreement between calculated and experimental values of magnetic susceptibilities is obtained. All compounds studied are found to be diamagnetic. According to the magnetic exaltation criterion all compounds studied are predicted to be aromatic. This result is supported in the case of annelated annulenes by the TRE criterion. However, the parent structures, [14] annulene and [18] annulene, are found by the TRE to be non-aromatic. Finally, it is found that the aromatic stability does not parallel inert reactivity, i.e., some highly aromatic annulenoids are predicted by the low HOMO—LUMO separation to be rather reactive and some low aromatic structures are predicted by the high HOMO—LUMO separation to exhibit a considerable reactive inertness.