Syntheses and structures of [UO2(L)5](ClO4)2 and [U(L')4(H2O)4](ClO4)4 (L is dimethylformamide, L' is N,N-dimethylcarbamide)

The reaction of aqueous solutions of uranyl perchlorate with selected organic amides was studied in the dark and under the sunlight. The complexes [(UO2)-O-VI(C3H7NO)(5)](ClO4)(2) (I) and [U-IV(C3H8N2O)(4)(De(2)D)(4)](ClO4)(4) (II), where C3H7NO is N,N-dimethylformamide (Dmfa) and C3H8N2O is N,N-dimethylcarbamide (a-Dmur), were studied by X-ray diffraction. Complex II and the complex U-IV(s-Dmur)(4)(De(2)D)(4)(ClO4)(4) (III), where s-Dmur is N,N'-dimethylcarbamide, were studied by IR spectroscopy. Crystals I and II are composed of mononuclear [UO2(Dmfa)(5)](2+) and [U(Dmur)(4)(De(2)D)(4)](4+) groups as uranium-containing structural units belonging to the crystal-chemical groups ADe (7) (1) (D = U-VI, De(1) = O2- and Dmfa) and ADe(8)(1) (D = U-IV, De(1) = Dmur and De(2)D) of uranium complexes, respectively. The mononuclear uranium- containing complexes in the crystals of U(IV) and U(VI) perchlorates were found to obey the 14 neighbors rule.