Nitrate and perchlorate complexes of uranium(IV).

The solid-state structures of the [U(IV)(NO(3))(6)](2-) anions in the [n-Pr(4)N](2)[U(NO(3))(6)] (1), [n-Bu(4)N](2)[U(NO(3))(6)] (2), and [Ph(4)P](2)[U(NO(3))(6)] x 4 NCCH(3) (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 U(IV) 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 [U(IV)(ClO(4))(6)](2-) anion using the analogous route resulted in the isolation of U(ClO(4))(4)(NCCH(3))(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.