Crystal Structure and Thermal Behaviour of K2[CrF5·H2O]

K2[CrF5·H2O] is monoclinic: a = 9.6835(3) A, b = 7.7359(2) A, c = 7.9564(3) A, β = 95.94(1)°, Z = 4, space group C2/c (no 15). Its crystal structure was solved from its X-ray powder pattern recorded on a powder diffractometer, using for the refinement the Rietveld method. It is built up from isolated octahedral [CrF5·OH2]2− anions separated by potassium cations. The dehydration of K2[CrF5·H2O] leads to anhydrous orthorhombic K2CrF5: a = 7.334(2) A, b = 12.804(4) A, c = 20.151(5) A, Z = 16, space group Pbcn (no 60), isostructural with K2FeF5.