Reactions have been studied between uranium hexafluoride and a series of lower fluorides of other elements. The study has also included reaction with a wide range of covalent chlorides. The reactivity of uranium hexafluoride is compared with that of the higher fluorides of d-transition elements, chromium, molybdenum, and tungsten, and considered in the light of uranium as an f-transition element.Considering the technological importance of uranium hexafluoride it is surprising that its chemistry has received so little attention. In this context Katz and Seaborg have commented:1 "By comparison with the research carried out on its physical properties, much remains to be done on the chemical properties and reactions of uranium hexafluoride."There are reports of reactions of uranium hexafluoride with substances such as carbon disulfide,2 hydrogen sulfide,2 carbon tetrachloride,3 nitric oxide,4 5nitryl and nitrosyl fluorides,6 hydrogen halides,6 and ammonia.7 There is a brief wartime report of reactions with phosphorus trichloride, silicon tetrachloride, and thionyl chloride.8 However, there is no simple relationship between these compounds, and it is impossible to use them to systematize the reactivity of uranium hexafluoride.In earlier studies we have carried out a systematic series of reactions of the higher fluorides of the subgroup VI elements molybdenum,9-10 tungsten,10 and chromium.10 These reactions were designed to show the ability of the higher transition metal fluorides to oxidize lower fluorides of group V elements or to enter into halogen-exchange reactions with covalent chlorides such as those of groups IV and V. Historically uranium has been considered an element of subgroup VI, but in recent years it has seemed more reasonable to consider it a member of the actinide series. Therefore, it seemed of interest to subject uranium hexafluoride to a series of reactions similar to those used with the higher fluorides of chromium, molybdenum, and tungsten to seek further information on whether uranium acts as a d-type or f-type transition element; that is, what similarities and differences exist between

No abstract

An earlier investigation of the reactions of higher fluorides of transition elements with a range of covalent chlorides has now been extended to cover the reactions of the hexafluorides of molybdenum, tungsten, and uranium with binary ionic chlorides. The observed results correlate well with published thermodynamic data.

Bei der thermischen Zersetzung von UO4.

"UFg wird in" Gegenwart von HF durch H, bei Raumtemperatur zu UiFs reduziert.