[en] The [(UO₂)₂F₆-2H₂O]^2- ion has been observed in the Cs₂[(UO₂)2F₆-2H₂O] compound. It is similar to the (UO₂)₂F₈^4- ion already found in the Cs₄(UO₂)₂F₈-2H₂) and Rb₄(UO₂)₂F₈-2H₂O complexes in which two of the fluorine atoms are replaced by two water molecules. Because of the existence of hydrogen bonds, these ions group themselves together in this structure to form chains