This analysis revealed that the pentalenide core was clearly aromatic in all compounds but to different extents. The ACID plot of 1 showed a strong diatropic (aromatic) ring current around the C8 perimeter of the pentalenide system, excluding the transannular C-C bond (Figure , top). This finding is consistent with previous MO analyses showing haptotropic mobility of Lewis-acidic metals bound to the dianionic 10π system to be confined to the perimeter, with a forbidden path across the central C-C bridge due to unfavourable orbital overlap. The ACID plots of 2 (Figure ) and 3 (Figure ) showed global diatropic ring currents within the pentalenide system as well, but with a larger contributions of the transannular C-C bond, in addition the individual diatropic ring currents in the four aromatic substituents.