Alternation of aromatic-nonaromatic rings in belt-like structures. The behavior of [6.8](3)cyclacene in magnetic fields.

[6.8]3Cyclacene is an interesting belt-like structure displaying aromatic-non-aromatic alternation, which is useful to gain an understanding of the intramolecular and intermolecular interactions between the anisotropic cones in the magnetic behavior of such rings. From the analysis of certain components in an induced magnetic field and (13)C-NMR shielding under its own principal axis system (PAS), the individual and overall magnetic behavior of each respective aromatic and non-aromatic fragments can be clearly described. Interestingly, the magnetic response of [6.8]3cyclacene suggests a characteristic behavior given by its confinement into a belt-like structure.