Structure of some complex halides of uranium(III)

Polycrystals of some halide complexes of uranium(III) were obtained and investigated by x-ray diffraction. The M2UCl5 compounds (M = K, Rb) are isostructural with K2PrCl5; RbU2Cl7 is of the same type as RbDy2Cl7 or KDy2Cl7. The coordination number of the uranium is 7. The M2UBr5 compounds (M = K-Cs) are isostructural with Cs2DyCl5, and the coordination number of the uranium is 6. Rb2NaUCl6 is a 12L-hexagonal polytype, the structural analog of Cs2NaCrF6. The most characteristic coordination number of uranium in the UHal3-MHal systems is 8 for Hal = F, 7 for Hal = Cl, and 6 for Hal = Br