Abstract

The NMR characterization of small C(36)hollow fullerene exposes a stable cage with structural features based on its strained curved pi-surface in aD(6h)-symmetry. Our results indicate that planar-like aromatic properties of theD(6h)-C(36)isomer decrease to a nonaromatic cage forD(2d)-C(36)after Stone-Wales transformation of an equatorial [6.6] bond. This is given by the decrease of conjugation in the strained pi-surface after Stone-Wales transformation. Calculated nuclear shielding shows that the main shielding component is always oriented perpendicularly to the cage pi-surface despite the larger curvature degree, as a result of the sp(2)character of carbon atoms, resembling C-60. Moreover, theD(6h)- andD(2d)-C(36)cages differ in their charge distribution properties, leading to charge accumulation in the strained cap of the former that leads to a polymerization-prone cage, which contrasts with that expected for theD(2d)structure. Hence, structural rearrangements of these non-Hirsch aromatic fullerenes show that their inherent global behavior requires considering the structural features besides electron counting rules.