Nb₃Cl₈ (Niobium Chloride)

A layered van der Waals cluster compound isostructural with Nb₃Br₈, in which Nb₃ triangular clusters arrange on a breathing kagome lattice, each cluster hosting one unpaired electron. It is a Mott-insulating magnetic semiconductorfeaturing flat electronic bands and an obstructed atomic (topological) insulating state, and undergoes a magnetic-singlet structural transition upon cooling. These properties make Nb₃Cl₈ an important platform for studying flat-band correlated physics, cluster magnetism, and spin-filtering barrier layers.