Niobium(V) fluoride, also known as niobium pentafluoride, is the inorganic compound with the formula NbF5. The solid consists of tetramers [NbF5]4. It is a colorless solid that is rarely used. Preparation and reactions Niobium pentafluoride is obtained by treatment of any niobium compound with fluorine: 2 Nb + 5 F2 → 2 NbF5 2 NbCl5 + 5 F2 → 2 NbF5 + 5 Cl2 It reacts with hydrogen fluoride to give H2NbF7, a superacid. Related compounds In hydrofluoric acid, NbF5 converts to [NbF7]2- and [NbF5O]2-. The relative solubility of these potassium salts and related tantalum fluorides is the basis of the Marignac process for separation of Nb and Ta. NbCl5 forms a dimeric structure (edge-shared bioctahedron) in contrast to the corner-shared tetrameric structure of the fluoride. External links NIST Standard Reference Database References Niobium(V) compounds Fluorides Metal halides