Actinide fluorides

Dioxygea difluoride has fouad some appHcatioa ia the coaversioa of uranium oxides to UF (66), ia fluoriaatioa of actinide fluorides and oxyfluorides to AcF (67), and in the recovery of actinides from nuclear wastes (68) (see Actinides and transactinides Nuclear reaction, waste managel nt). 

Structural systematics in actinide fluoride complexes. R. A. Permman, R. R. Ryan and A. Rosen-zweig, Struct. Bonding (Berlin), 1973,13,1-52 (174). 

Penneman RA, Ryan RR, Rosenzweig A (1973) Structural Systematics in Actinide Fluoride Complexes. 13 1-52... 

Metallothermic reduction of an actinide halide was the first method applied to the preparation of an actinide metal. Initially, actinide chlorides were reduced by alkali metals, but then actinide fluorides, which are much less hygroscopic than the chlorides, were more... 

Excellent quality metal, comparable to that from the halide reduction, can be prepared by this technique. A big advantage is that no neutrons are present from (a,ra) reactions on fluorine nuclei, in marked contrast to the case with actinide fluorides. 

The ions of the first members of the second and third transition series (Me + = Y, La and Me + = Zr, Hf) are so large, as to achieve higher C.N.s than 6 already in some compounds AMe +F4 (page 33) and AgMe +Fj (47, 42) as well as in their binary fluorides (pages 37, 30). To deal with these structures which correspond closely to those of the lanthanide and actinide fluorides, is beyond the scope of this review. As for the stereochemistry of 8-coordination the reader is referred to papers by Clark et al. 68) and Kepert 189). 

The silicides of the actinides have not been widely characterized. A uranium sihcide of the form U3Si2 has received the maximum amount of study owing to its nse as a dispersion fuel in research reactors. Another common phase observed for actinide silicides is AnSi2. One of the common synthetic routes to the silicides is the reaction of actinide fluorides, for example, Anp4, with elemental Si at high temperatures. One of the thermodynamic driving forces for this reaction is the release of Sip4. 

Choppin, G. R., and Unrein, P. J. Thermodynamic study ot actinide fluoride complexation, p. 97-107, in Muller, W. and Lindner, R., eds., "Transplutonium Elements," North-Holland Publ. Co., Amsterdam, 1976. 

Solid Compounds. The literature (2, 5, 8, 9, 12) on solid actinide fluoride complexes is extensive, and many new compounds are being prepared. For example, Thoma, Friedman, and Penneman (12) reported the first preparation of complex fluorides formed between UF3 and the alkali fluorides KF, RbF, and CsF. This section summarizes the work which was performed concerning the solid compounds resulting from neptunium in saturated KF solution. 

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