Nitrate and Perchlorate Complexes of Uranium(IV)

The solid-state structures of the [UIV(NO3)6]2- anions in the [n-Pr4N]2[U(NO3)6] (1), [n-Bu4N]2[U(NO3)6] (2), and [Ph4P]2[U(NO3)6]·4NCCH3 (3) salts were determined using single-crystal X-ray diffraction. For the first time, a nondisordered structure of the hexanitratouranate(IV) dianion with a coordination number of 12 for the central UIV atom was determined. Salts 1−3 were prepared in simple metathesis reactions and characterized using IR spectroscopy, C/H/N analysis, and single-crystal X-ray diffraction. Attempts to prepare a salt containing the [UIV(ClO4)6]2- anion using the analogous route resulted in the isolation of U(ClO4)4(NCCH3)5 (4), which was characterized using single-crystal X-ray diffraction. Compound 4 is the first structurally characterized uranium(IV) perchlorate to be reported in the literature.