Diradicals as Topological\nCharge Carriers in Metal–Organic\nToy Model Pt<sub>3</sub>(HIB)<sub>2</sub>

We explore the eclipsed stacking of a metal–organic\nKagome\nlattice containing heavy-metal nodes. Our model is Pt<sub>3</sub>(HIB)<sub>2</sub>, a hypothetical but viable member of a well-known family\nof hexaaminobenzene based metal–organic frameworks (MOFs).\nApplying space group theory, it is shown how molecular diradicals,\nbrought into play by a noninnocent ligand, become topologically nontrivial\nbands when moving in a periodic potential. Three factors are required\nto enable this: (1) eclipsed stacking, which shifts the Fermi level\nnear a symmetry-protected band crossing (2) the emergence of an electride-like\nband that renders the topological Z2 invariant equal to 1, thus nontrivial,\nand (3) Pt-induced spin–orbit coupling, to turn the crossing\ninto a bulk band gap. The electride band, with its unforeseen role,\nbears kinship to the interlayer band in hexagonal superconductors.\nIt places its charge density in the voids of the crystal, rather than\naround the atomic nuclei, and we name it a “pore band”.\nWhile the synthesis of truly conductive MOFs has proven challenging,\nthe analysis shows that intrinsically nonlocal physics may emerge\nfrom tunable molecular building blocks. With the richness of redox-active\nMOF chemistry, this offers a pathway to tailored topological electronics.