AbstractXenon difluoride forms a 1:1 complex with XeOF4(m.p. 29°C) which is isostructural with XeF2· IF5. The unit cell is tetragonal with a = 7.56(2), c = 11.36(3) Å, V = 647 Å3, z = 4. RAMANdata prove it to be a molecular complex, the structure of which is compatible with appreciable bond polarity in XeF2. Similar interactions of XeF2with the XeF+5cation are indicated by the RAMANspectra of the complexes which XeF2forms with [XeF5]+[AsF6]−. The spectrum of the 1:2 complex indicates that the XeF2molecule is undistorted but the spectrum of the 1:1 complex suggests that the XeF2molecule is distorted by interaction with XeF+5ions. The occurrence of molecular XeF2in the XeF+5AsF6lattice confirms the superiority of XeF6to XeF2as a fluoride ion