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The molten boric acid flux reaction of PuBr(3) with KBO(2) at 200 °C results in the formation of large light-yellow crystals of K[B(5)O(7)(OH)(2)]·H(2)O:Pu(4+). Single-crystal X-ray diffraction experiments on the Pu-doped K[B(5)O(7)(OH)(2)]·H(2)O demonstrate two features: (1) K[B(5)O(7)(OH)(2)]·H(2)O:Pu(4+) adopts a one-dimensional borate chain structure with void spaces between the chains. (2) The doping plutonium atoms do not reside on the potassium sites. The latter are not fully occupied. Both laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and energy-dispersive spectrometry analyses indicate that plutonium atoms are uniformly distributed in crystals of K[B(5)O(7)(OH)(2)]·H(2)O with an atomic K:Pu ratio of approximately 65:1 measured by LA-ICP-MS. UV-vis-NIR spectra taken from both freshly made and one day old crystals show that the plutonium present within the crystals is predominantly characterized by Pu(IV). A small amount of Pu(III) is also present initially, but slowly oxidized to Pu(IV) via interaction with oxygen in the air. X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopic measurements confirm that plutonium is mainly present as a form similar to that of a PuO(2) cluster. The combined results suggest that the clusters containing Pu(IV) ions are uniformly distributed in the void spaces between the borate chains.

U(VI), Np(VI), and Pu(VI) borates with the formula AnO(2)[B(8)O(11)(OH)(4)] (An = U, Np, Pu) have been prepared via the reactions of U(VI) nitrate, Np(VI) perchlorate, or Pu(IV) or Pu(VI) nitrate with molten boric acid. These compounds are all isotypic and consist of a linear actinyl(VI) cation, AnO(2)(2+), surrounded by BO(3) triangles and BO(4) tetrahedra to create an AnO(8) hexagonal bipyramidal environment. The actinyl bond lengths are consistent with actinide contraction across this series. The borate anions bridge between actinyl units to create sheets. Additional BO(3) triangles and BO(4) tetrahedra extend from the polyborate layers and connect these sheets together to form a three-dimensional chiral framework structure. UV-vis-NIR absorption and fluorescence spectroscopy confirms the hexavalent oxidation state in all three compounds. Bond-valence parameters are developed for Np(VI).

The first plutonium(III) borate, Pu(2)[B(12)O(18)(OH)(4)Br(2)(H(2)O)(3)]·0.5H(2)O, has been prepared by reacting plutonium(III) with molten boric acid under strictly anaerobic conditions. This compound contains a three-dimensional polyborate network with triangular holes that house the plutonium(III) sites. The plutonium sites in this compound are 9- and 10-coordinate and display atypical geometries.

The in situ hydrothermal reduction of Np(VI) to Np(IV) and Pu(VI) to Pu(IV) in the presence of 1,2-phenylenediphosphonic acid (PhP2) results in the crystallization of Np[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O (NpPhP2) and Pu[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (PuPhP2), respectively. Similar reactions have been explored with Ce(IV) resulting in the isolation of the Ce(IV) phenylenediphosphonate Ce[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (CePhP2). Single crystal diffraction studies reveal that although all these three compounds all crystallize in the triclinic space group P1̅, only PuPhP2 and CePhP2 are isotypic, whereas NpPhP2 adopts a distinct structure. In the cerium and plutonium compounds edge-sharing dimers of MO(8) polyhedra are bridged by the diphosphonate ligand to create one-dimensional chains. NpPhP2 also forms chains. However, the NpO(8) units are monomeric. The protonation of the ligands is also different in the two structure types. Furthermore, the NpO(8) polyhedra are best described as square antiprisms (D(4d)), whereas the CeO(8) and PuO(8) units are trigonal dodecahedra (D(2d)). Bond-valence parameters of R(o) = 1.972 and b = 0.538 have been derived for Np(4+) using a combination of the data reported in this work with that available in crystallographic databases. The UV-vis-NIR absorption spectra of NpPhP2 and PuPhP2 are also reported and used to confirm the tetravalent oxidation states.

Research has been conducted on neptunyl(VI) iodates. The authors describe the preparation of these compounds in HCl via aqueous reactions of Np(V) with KIO (sub)4, and their characterization via single-crystal X-ray diffraction and Raman spectroscopy.

PuL2 and CeL2 (L = N,N′-bis[(4,4′-diethylamino)salicylidene]-1,2-phenylenediamine) have been synthesized, and characterized by single crystal X-ray diffraction, UV/vis/NIR spectroscopy, and cyclic voltammetry. These studies reveal the enhanced stabilization of Pu(iv) versus Ce(iv) with this Schiff base, and quasi-reversible redox behaviour only with the plutonium complex. [ABSTRACT FROM AUTHOR]

The reactions of trivalent lanthanides and actinides with molten boric acid in high chloride concentrations result in the formation of M4[B16O26(OH)4(H2O)3Cl4] (M=Sm, Eu, Gd, Pu, Am, Cm, Cf). This cubic structure type is remarkably complex and displays both chirality and polarity. The polymeric borate network forms helical features that are linked via two different types of nine-coordinate f-element environments. The f-f transitions are unusually intense and result in dark coloration of these compounds with actinides. [ABSTRACT FROM AUTHOR]

The reactions of LnCl3 · 6 H2O with molten boric acid result in the formation of three different products depending on the identity of the lanthanide metal. The analogous reactions using AnCl3 · 6 H2O (An = Pu(III), Am(III), and Cm(III) with molten boric acid under the same conditions do not yield the same results as those of the 4f series or of the other 5f elements. For the most part, the actinide products obtained have no lanthanide analogues making them unique compounds. Furthermore, the reactions of LnX3 · yH2O (X = Br, I) (Ln = La-Nd) with molten boric acid results in the formation of two products. The analagous set of reactions was performed with PuX3 · yH2O (X = Br, I) which, yet again, gave rise to completely novel compounds. All of these compounds are three-dimensional framework structures comprised of sheets. These sheets are made up of both BO3 and BO4 units which are arranged in such a maner that creates triangular holes in which the lanthanide or actinide sites reside. The borate units of the triangular holes provide six oxygen atoms that coordinate in the equatorial region resulting in unique nine- and/or ten-coordinate geometries. The similarities and differences between the 4f and 5f borate compounds are discussed with particular emphasis on the periodic trends of this system. [ABSTRACT FROM AUTHOR]

Synthesis of a plutonium (III) molybdate bro-mide, PuMoO4Br(H2O), has been accomplished using hydro-thermal techniques in an inert-atmosphere glovebox. The compound is green in color, which is in stark contrast to the typical blue color of plutonium (III) complexes. The unusual color arises from the broad charge transfer (CT) spanning from approximately 300 to 500 nm in the UV--vis--near-IR spectra. Repeating the synthesis with an increase in the reaction temperature results in the formation of a plutonium-(IV) molybdate, PU3MO6O24(H2O)2, which also has a broad CT band and red-shifted f--f transitions. Performing an analogous reaction with neodymium produced a completely different product, [Nd(H2O)3][NdMo12O42]-2H2O, which is built of Silverton-type polyoxometallate clusters. [ABSTRACT FROM AUTHOR]

The hydrothermal reaction of PuCl3 or CeCl3 with TeO2 in the presence of sulfuric acid under the comparable conditions results in the crystallization of Pu(TeO3)(SO4 ) or Ce2(Te2O5)(SO4)2, respectively. Pu- (TeO3)(SO4 ) and its isotypic compound Th(TeO3)(SO4 ) are characterized by a neutral layer structure with no interlamellar charge-balancing ions. However, Ce2(Te2O5)(SO4)2 possesses a completely different dense three-dimensional framework. Bond valence calculation and UV--vis--NIR spectra indicate that the Ce compound is trivalent whereas the Pu and Th compounds are tetravalent leading to the formation of significandy different compounds. Pu(TeO3)(SO4), Th(TeO3)(SO4), and Ce2(Te2O5)(SO4)2 represent the first plutonium/thorium/cerium tellurite sulfate compounds. Our study strongly suggests that the chemistries of Pu and Ce are not the same, and this is another example of the failure of Ce as a surrogate. [ABSTRACT FROM AUTHOR]

The hydrothermal reactions of trivalent lantlia- nide and actinide chlorides with 1,2-methylenediphosphonic acid (C1P2) in the presence of NaOH or NaN03 result in the crystallization of three structure types; RE[CH2(PO3H0.5)2] (RE = La, Ce, Pr, Nd, Sm; Pu) (A type), NaRE(H2O)- [CH2(P03)2](RE - La, Ce, Pr, Nd, Sm, Eu, Gd, Tb. Dy; Am) (B type), or NaLn[CH2(P03Ho5)2]-(H20) (Ln = Yb and Lu) (C type). These crystals were analyzed using single crystal X- ray diffiraction, and the structures were used directly for detailed bonding calculations. These phases form three-dimensional frameworks. In both A and B, the metal centers are found in REO8 polyhedra as parts of edge-sharing chains or edge-sharing dimers, respectively. Polyhedron shape calculations reveal that A favors a D2d dodecahedron while B adopts a C2p geometry. In C, Yb and Lu only form isolated MO6 octahedra. Such differences in terms of structure topology and coordination geometry are discussed in detail to reveal periodic deviations between the lanthanide and actinide series. Absorption spectra for the Pu(III) and Am(III) compounds are also reported. Electronic structure calculations with multireference methods, CASSCF, and density functional theory, DFT, reveal localization of the An Sf orbitals, but natural bond orbital and natural population analyses at the DFT level illustrate unique occupancy of the An 6d orbitals, as well as larger occiancy of the Pu 5f orbitals compared to the Am 5f orbitals. [ABSTRACT FROM AUTHOR]

The reactions of 237NpO2 with excess iodate under acidic hydrothermal conditions result in the isolation of the neptunium(IV), neptunium(V), and neptunium(Vl) iodates, Np(IO3)4, Np(lO3)4·nH2O·nHIO3, NpO2(IO3), NpO2(IO3)2- (H2O), and NpO2(IO3)2·H2O, depending on both the pH and the amount of water present in the reactions. Reactions with less water and lower pH favor reduced products. Although the initial redox processes involved in the reactions between 237NpO2 or 242PuO2 and iodate are similar, the low solubility of Pu(IO3)4 dominates product formation in plutonium iodate reactions to a much greater extent than does Np(IO3)4 in the neptunium iodate system. UO2 reacts with iodate under these conditions to yield uranium(Vl) iodates solely. The isotypic structures of the actinide- (IV) iodates, An(IO3)4 (An = Np, Pu), are reported and consist of one-dimensional chains of dodecahedral An(IV) cations bridged by iodate anions. The structure of Np(IO3)4·nH2O·nHlO3 is constructed from NpO9 tricapped-trigonal prisms that are bridged by iodate into a polar three-dimensional framework structure. Second-harmonic-generation measurements on a polycrystalline sample of the Th analogue of Np(IO3)4·nH2O·nHlO3 reveal a response of approximately 12x that of α-SiO2. Single-crystal magnetic susceptibility measurements of Np(IO3)4 show magnetically isolated Np(IV) ions. [ABSTRACT FROM AUTHOR]

Reactions of oxides or halides of trivalent lanthanides and actinides or Bi with H3BO3 in the ionic liquid [bmim]Cl in the presence of a small amount of water (autoclave, 150 °C, 5 d; controlled cooling) result in the crystallization of a series of isomorphous tetranuclear borate clusters of general formula M4B22O36(OH)6 (H2O)13 (M: La, Ce, Pr, Nd, Sm, Eu, Gd, Pu, and Bi). [ABSTRACT FROM AUTHOR]

MoO3 and HBr-reduced weapons-grade PuOCl2 or NdBr3 are used for the hydrothermal synthesis of PuIIIMoO4Br(H2O) (I), PuIV3Mo6O24 (H2O)2 (II), and [Nd(H2O)3] [NdMo12O42]·2H2O (III) (PTFE-lined autoclave, 200 °C for (I) and (III), 230 °C for (II), 3 d). [ABSTRACT FROM AUTHOR]

Pu(TeO3)(SO4) (I), Ce2(Te2O5)(SO4)2 (II), and Th(TeO3)(SO4) (III) are prepared by hydrothermal reaction of weapons-grade PuCl3, CeCl3 (CeO2), or Th(OH)4, resp. [ABSTRACT FROM AUTHOR]

Compounds (III) and (V) are isotypic and crystallize in the triclinic space group P $\bar 1$ with Z = 2 (single crystal XRD). [ABSTRACT FROM AUTHOR]