Hexafluorouranate

Uranium hexafluoride, the building block of hexafluorouranates.

Hexafluorouranate is an octahedral^[1] anion made of six fluorine atoms and one uranium atom. It is most commonly found in the +4 or +5 oxidation states. It can be produced by combining cations with uranium hexafluoride.

Examples of hexafluorouranates

There are six alkali metal hexafluorouranates, which include lithium, sodium, potassium, rubidium, and two salts of caesium, one of which uses the uranium in the +4 oxidation state, the other in +5.^[1][2][3]

Other metallic hexafluorouranates include copper, silver, cadmium, and thallium.^[1][4]

Nitrogen-oxygen hexafluorouranates include nitrosonium and nitronium, the first of which can be combined with an alkali metal nitrate to form the alkali metal hexafluorouranate.^[5][1]

Other hexafluorouranates include hydrogen, hydroxylammonium, oxonium, bis(acetonitrile)iodine, tris(acetonitrile)bromine, dicarbonylgold, bis(carbonyl)silver, and tetraethylammonium.^{[6][7][8][9][10]}

Bis(acetonitrile)iodine and tris(acetonitrile)bromine are synthesized by letting iodine or bromine get oxidized by uranium hexafluoride in acetonitrile. So far, we have only synthesized it with these two halogens, but theoretically, chlorine and fluorine should work too.^[7][8]

Reactions

Nitrosonium hexafluorouranate, when combined with any alkali metal nitrate from lithium to caesium can create the alkali metal hexafluorouranate along with two nitrogen dioxide molecules.^[1]

References

1. Scheibe, Benjamin; Wassermann, Tobias B.; Kraus, Florian (2025-09-15). "Syntheses, Single-Crystal Structures, and Structural Chemistry of Hexafluoridouranates(V), MUF6 (M = Li-Cs, Ag, Tl, H3O), and the Dodecafluoridodiuranate(V) Ba[U2F12]·1.36HF". Inorganic Chemistry. 64 (36): 18432–18446. doi:10.1021/acs.inorgchem.5c03005. ISSN 1520-510X. PMC 12442095. PMID 40904026.
2. Volkov, V. A.; Suglobova, I. G.; Chirkst, D. Eh (April 1981). "Structure of alkali metal fluorouranates (3)". Izv. Akad. Nauk SSSR, Neorg. Mater. (in Russian). 17 (4): 707–711. ISSN 0002-337X.
3. Malm, J. G. (1979). "The reaction of cesium and sodium metals with uranium hexafluoride". J. Inorg. Nucl. Chem. 41 (11): 1573–1575. ISSN 0022-1902.
4. Berry, John A.; Poole, Ronald T.; Prescott, Ann; Sharp, David W. A.; Winfield, John M. (1976-01-01). "The oxidising and fluoride ion acceptor properties of uranium hexafluoride in acetonitrile". Journal of the Chemical Society, Dalton Transactions (3): 272–274. doi:10.1039/DT9760000272. ISSN 1364-5447.
5. "Nitrosylium Hexafluorouranate (NOUF6) and Its Derivatives". pubs.acs.org. doi:10.1021/acs.inorgchem.6c00058. Retrieved 2026-04-23.
6. Frlec, Boris; Hyman, Herbert H. (1967-12-01). "Hydrazinium (+2) and hydroxylammonium hexafluorouranates (v)". Inorganic Chemistry. 6 (12): 2233–2239. doi:10.1021/ic50058a023. ISSN 0020-1669.
7. "K:\STM_UK\e-ErosII\Book\U\ru.dvi" (PDF). Retrieved April 23, 2026.
8. McGhee, Laurence; Rycroft, David S.; Winfield, John M. (August 1987). "Oxidation of molecular bromine by uranium hexafluoride in acetonitrile. Preparation and properties of hexafluorouranates(V) containing positive bromine". Journal of Fluorine Chemistry. 36 (3): 351–359. doi:10.1016/S0022-1139(00)82077-1. ISSN 0022-1139.
9. Wassermann, Tobias B.; Karttunen, Antti J.; Kraus, Florian (August 2, 2025). "[Au(CO)2][UF6]–Synthesis, Crystal Structure, Raman Spectroscopy, and Quantum-Chemical Calculations of the Nonclassical Carbonyl Compound". Retrieved April 24, 2026.
10. Pedersen, Kasper S.; Meihaus, Katie R.; Rogalev, Andrei; Wilhelm, Fabrice; Aravena, Daniel; Amoza, Martin; Ruiz, Eliseo; Long, Jeffrey R.; Bendix, Jesper; Clerac, Rodolphe (August 2019). "[UF6]: A Molecular Hexafluorido Actinide(IV) Complex with Compensating Spin and Orbital Magnetic Moments". Retrieved April 24, 2026.