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Precipitation of salts M[NpO(OH)]· nHO (M = Na, K, Rb, Cs) from concentrated alkali solutions at low temperatures (about −10°C) was studied. From solutions with [OH] > 9.5 M, these compounds are isolated as coarse black crystals in high yield without impurity of other phases. The K, Rb, and Cs salts crystallize in the form of the previously studied compounds K[NpO(OH)]·2HO and M[NpO(OH)]·3HO (M = Rb, Cs). In the case of Na, a new hydrate Na[NpO(OH)]·6HO was obtained, and its crystal structure was determined. Crystals of the hexahydrate consist of centrosymmetrical tetragonal-bipyramidal anions [NpO(OH)], crystallographically independent Na(1) and Na(2) cations, and water molecules. The coordination surrounding of the Np atom is characterized by noticeable difference (Δ = 0.0203 Å) in the Np-O bond lengths in the equatorial plane of the bipyramid. The [NpO(OH)] anions are combined with the Na(2) cations to form infinite chains [Na(2)NpO(OH)(HO)] in such a manner that the lateral edges of the anion are simultaneously the lateral edges of the Na(2) coordination polyhedron. Incorporation of one of the two crystallographically independent O atoms of the NpO group into the Na(2) coordination surrounding is responsible for a noticeable difference in the Np-O bond lengths in the equator of the [NpO(OH)] anion. The types of hydrogen bonding in the structures of Na3[NpO(OH)]· nHO ( n = 0, 2, 4, 6) are compared. [ABSTRACT FROM AUTHOR]

Complexes of 1,10-phenanthroline (phen) with Np(V) and Pu(V) benzoates of the compositions NpO2(phen)(OOCC6H5) and PuO2(phen)(OOCC6H5) were synthesized. A powder X-ray diffraction study showed that these compounds, depending on the preparation conditions, exist in the form of two phases having essentially the same composition but different powder patterns. The phases isolated from hot (70–100°C) solutions are isostructural with the previously described complexes AnO2(bipy)(OOCC6H5) (An = Np and Pu, bipy = 2,2′-bipyridine), i.e., in their structure there are dimeric (AnO2) cations formed by mutual coordination of two AnO ions via “yl” oxygen atoms. The compounds AnO2(phen)(OOCC6H5) prepared by slow crystallization in the cold or at weak (up to 45°C) heating are isostructural with each other but appreciably differ in the structure from the high-temperature phases. The electronic absorption spectra of the compounds and their thermal behavior were examined. [ABSTRACT FROM AUTHOR]

Double Pu(V) and Np(V) acetates of the compositions BaPuO2Ac3·2H2O and SrAnO2Ac3·3H2O with An = Pu and Np were synthesized in a well-crystallized form. In the dry state the compounds are stable in prolonged storage and are not hygroscopic. The plutonyl(V) and neptunyl(V) salts of the similar composition are isostructural. The IR spectra of the compounds were measured, and their behavior in heating was studied. [ABSTRACT FROM AUTHOR]

New crystalline compounds of the general composition Co(NH3)6[PuO2L]2A · nH2O, where L = CH2(COO)2 and A = HCOO, CH3COO, C2H5COO, and HL, were prepared by adding a small excess of Co(NH3) ions to freshly prepared neutral Pu(V) malonate solutions containing single-charged organic anions. The complexes are sparingly soluble in water and fairly stable when stored in air; they have a similar structure. Previously unknown double Np(V) malonates Co(NH3)6[NpO2L]2A · nH2O, where A = HCOO, CH3COO, and C2H5COO, isostructural with the corresponding Pu(V) compounds, were also prepared. The IR spectra of the new compounds were measured, and their behavior at heating was examined. [ABSTRACT FROM AUTHOR]

New crystalline compounds of the composition Co(NH3)6[PuO2L]2A ⋅ nH2O, where L = C3H2O4 and A = NO3, ClO4, Cl, and Br, were obtained by addition of a small excess of Co(NH3) ions to freshly prepared neutral malonate solutions of Pu(V). They are fairly stable in storage in air and isostructural to the corresponding Np(V) compounds. Thermal behavior of the compounds synthesized was studied, and their IR spectra were measured. [ABSTRACT FROM AUTHOR]

Preparation conditions and properties of some double Pu(V) malonates MPuO2L · nH2O [L = CH2(COO)2; M = Na, NH4, Cs] were determined. These compounds are isostructural to the corresponding double Np(V) malonates obtained previously. The Pu(V) malonates crystallize in the form of needles from solutions with [L2−] = 0.05–0.3 M containing 0.5–2 M of salts of outer-sphere cations as salting- out agents. Dry crystals are stable for no less than 3 weeks. The IR spectra of these compounds were recorded. Their thermal behavior was studied. The outer-sphere cations presumably form ionic bonds with plutonyl(V) cations, which are weakened with an increase in the cation radius. [ABSTRACT FROM AUTHOR]