Copper(I) fluoride or cuprous fluoride is an inorganic compound with the chemical formula CuF.
It was reported in 1933 to have a sphalerite-type crystal structure.
[3] Modern textbooks state that CuF is not known,[4] since fluorine is so electronegative that it will always oxidise copper to its +2 oxidation state.
[5] Complexes of CuF such as [(Ph3P)3CuF] are, however, known and well characterised.
[6] Unlike other copper(I) halides like copper(I) chloride, copper(I) fluoride tends to disproportionate into copper(II) fluoride and copper in a one-to-one ratio at ambient conditions, unless it is stabilised through complexation as in the example of [Cu(N2)F].