Niobium(IV) fluoride is a chemical compound with the formula . It is a nonvolatile black solid.
absorbs vapor strongly and turns into in moist air. It reacts with water to form a brown solution and a brown precipitate whose components are unknown. It is stable between 275 °C and 325 °C when heated in a vacuum. However, it disproportionates at 350 °C rapidly to form niobium(V) fluoride and niobium(III) fluoride:[1]
(at 350 °C)
Niobium(IV) fluoride adopts a crystal structure analogous to that of tin(IV) fluoride, in which each niobium atom is surrounded by six fluorine atoms forming an octahedron. Of the six fluorine atoms surrounding a single niobium atom, four are bridging to adjacent octahedra, leading to a structure of octahedra connected in layers.