Abstract
The concept of fully benzenoid hydrocarbons (molecular graphs; FBHs) is generalized. Each full-hexagon unit (aromatic sextet) in a FBH is replaced with a larger “hexagon-shaped” unit (subgraph; e.g., naphthalene, pyrene, coronene, or ovalene units). Such a molecular species may be called a “fully hexagonoid” hydrocarbon (FHHs). The Pauling bond order calculation suggests that a bond (edge) which interlinks one hexagon-shaped unit with another in the bottom of bays of FHH is quasi-single, if the two units are connected by more than two bonds. As a consequence, the hexagon-shaped units are delocalized locally in the hexagonoidal (graph-theoretical) partitioning.