Clar's goblet, with delocalized unpaired electrons in its π-conjugated sp -carbon skeleton, structurally belongs to the category of graphene fragment radicals . These graphenic radicals possess distinct optical, electronic and magnetic properties, making them highly promising for applications in materials science . Two terms, "disjoint" and "non-disjoint" have been used to describe delocalized diradicals . In non-disjoint diradicals, such as Clar's hydrocarbon (triangluene) and trimethylenemethane (TMM) , two radicals can interchange positions through resonance structures (Fig. ). From the perspective of molecular orbital, two degenerate nonbonding molecular orbitals (NBMOs) spatially overlap, leading electrons to prefer unpaired spins to minimize repulsion, in accordance with Hund's rule . This triplet ground state of non-disjoint diradicals can be readily determined by sublattice imbalance by using Lieb's theorem or Ovchinnikov's rule . On the contrary, in Clar's goblet or tetramethyleneethane (TME) , two degenerate NBMOs are disjoint (i.e., have no atoms in common. Fig. ). The two radicals are only distributed in separate halves, based on resonance structure analysis (Fig. ). Consequently, the two electrons have no spatial overlap and do not need to obey Hund's rule. Furthermore, they tend to have opposite spins, although the mechanism is still unclear and may involve dynamic spin polarization . The calculated spin density distribution clearly illustrates the polarized distribution of the up and down spins in Clar's goblet (Fig. ). This unusual spin pairing between the two spatially separated electrons in Clar's goblet represents a form of spin entanglement . Although this local spin entanglement is far from practical application, pursuing demonstration of this property remains crucial for understanding quantum phenomena at the molecular level.