Nickel fluoride Nickel(ii) fluoride is the chemical compound with the formula nif2. Unlike many fluorides, nif2 is stable in air. Nif2 comprises the passivating surface that forms on nickel alloys, e.G. Monel, which is why such materials are good to store or transport hydrogen fluoride or elemental fluorine. Nickel is one of the few materials that can be used to store fluorine because it forms this coating. It is also used as a catalyst for the synthesis of chlorine pentafluoride. Fluoride compounds have diverse applications in current technologies and science, from oil refining and etching to syntheticorganic chemistry and the manufacture of pharmaceuticals. Synonyms Nickel(2+) difluoride, nickel (ii) fluoride, anhydrous, nickel difluoride, difluoronickel, nickelous fluoride