G. B. Andreev

Polymeric structure of oxalato-bridged complexes of tetravalent actinides Th, U, Np and Pu.

A series of isostructural oxalates of Th, U, Np, and Pu have been synthesized. The crystal structure of {C(NH(2))(3)}(4)[An(C(2)O(4))(4)]·2H(2)O comprises infinite [An(C(2)O(4))(4)](4n-) chains, guanidinium cations and water molecules. Each An atom is connected to five oxalate anions, two of which act as bridging tetradentate ligands, while the other three function as terminating bidentate ligands. Electron and IR spectra of the compounds as well as the results of thermal analysis correlate with their structure. An actinide contraction effect is demonstrated by a decrease in the An-O interatomic distances and the volumes of An atom coordination polyhedra and Voronoi-Dirichlet polyhedra. Ten-coordinate An oxalates are discussed in terms of continuous shape measures approach.

Synthesis and Structural Examination of Complexes of Am(IV) and Other Tetravalent Actinides with Lacunary Heteropolyanion α2-P2W17O6110-

This study concerns the formation of complexes with actinides at oxidation state +IV, from Th to Am, through a lacunary heteropolyanion ligand P(2)W(17)O(61)(10-). The preparation of original single crystals of complexes with 1:2 stoichiometry provided structural data through single-crystal X-ray diffraction for the entire An(IV) series. An(IV) atoms in these complexes have a coordination number of 8, and their coordination polyhedron is a distorted square antiprism. The data were used to compute a mean (An-O) interatomic distance for each actinide. When the interatomic distance is plotted versus the inverse ionic radius of these tetravalent actinides, it appears that the simple electrostatic model is not suitable for Am(IV) and Pu(IV), although this trend must be confirmed by further investigation with other examples from the An(IV) series.

Interaction of neptunium(V) with picolinic, nicotinic and isonicotinic acids

Summary The interaction of Np(V) with all isomers of pyridinemonocarboxylic acid has been investigated, stability constants have been calculated using NIR spectroscopy. Single crystals of [NpO2(Pic)(H2O)2] (1), Cs[NpO2(Pic)2(HPic)]·3H2O (2), [NpO2(Nic)(H2O)] (3), and [NpO2(iso-Nic)(H2O)] (4) have been synthesized. Compound 1 contains infinite chains; compound 2 consists of isolated Cs+, [NpO2(Pic)2(HPic)]- groups and water molecules. In both 3 and 4 neptunoyl-ion NpO2 acts as monodentate ligand with one of the O atoms of NpO2 group entering in coordination polyhedron of the adjacent Np atom. Compounds 3 and 4 have layered and three-dimensional topologies, respectively. Crystallographic data: [NpO2(Pic)(H2O)2], space group P¯1, triclinic, a = 6.380(2), b = 7.733(2), c = 10.700(4) Å, α = 96.49(3), β = 106.78(3), γ = 103.83(3)°, and Z = 2 (1); Cs[NpO2(Pic)2(HPic)]·3H2O, space group P¯1, triclinic, a = 8.707(2), b = 9.777(2), c = 14.640(3) Å, α = 76.633(15), β = 78.75(2), γ = 86.55(2)°, and Z = 2 (2); [NpO2(Nic)(H2O)], space group P21/n, monoclinic, a = 11.901(4), b = 5.5628(15), c = 12.124(3) Å, β = 101.05(2)°, and Z = 4 (3); [NpO2(iso-Nic)(H2O)], space group P212121, orthorhombic, a = 5.742(3), b = 8.550(5), c = 18.512(10) Å, and Z = 4 (4). Electron and IR spectra of solid compounds have been measured.

Neptunium(VI) Chromate Complex with 1,2-Diammoniopropane {H3NCH2CH(NH3)CH3}[(NpO2)2(CrO4)3(H2O)] · 3H2O: Synthesis, Crystal Structure and Properties

New neptunium(VI) complex {H3NCH2CH(NH3)CH3}[(NpO2)2(CrO4)3(H2O)] · 3H2O is synthesized; its crystal structure is determined and IR and near-IR absorption spectra are recorded. The crystallographic data are: a = 10.805(2) Å, b = 11.238(2) Å, c = 17.615(8) Å, space group P212121, Z = 4, V = 2139(1) Å3, R = 0.051, wR(F2) = 0.109. The crystal structure of the compound is built of the anionic layers of [(NpO2)2(CrO4)3(H2O)]2n–n. The {H3NCH2CH(NH3)CH3}2+ cations and crystallization water molecules are arranged between the layers. Coordination polyhedron of two crystallographically independent Np atoms has the shape of a pentagonal bipyramid. The equatorial plane in one Np polyhedron is formed by the oxygen atoms of four chromate ions and water molecule and by the oxygen atoms of five chromate ions in the other one.

Interaction of transuranium elements with biologically important ligands: structural and spectroscopic evidence for nucleotide coordination to plutonium.

The first complex of a transuranium element (tetravalent plutonium) with nucleotide (deoxycytidinemonophosphate, dCMP) was synthesized and structurally characterized. The crystal structure of [Pu(4)(NO(3))(8)(HdCMP)(4)(H(2)O)(8)](NO(3))(4).2H(2)O consists of complex cations [Pu(4)(NO(3))(8)(HdCMP)(4)(H(2)O)(8)](4+), NO(3)(-) anions, and water molecules. There are two crystallographically independent Pu atoms in the structure, both having similar surroundings. Each of the Pu atoms is coordinated by three O atoms of phosphate groups belonging to three different (HdCMP)(-) anions, two bidentate nitrate anions, and two water molecules. The crystal structure is confirmed by IR and UV/vis/near-IR spectroscopic data.

Crystal Structure and Absorption Spectra of Triguanidinium Bis(N-methyliminodiacetato)dioxoneptunate(V) {C(NH2)3}3[NpO2(mida)2]

This paper is a continuation of our on-going program for studying the structure and properties of pentavalent neptunium compounds with organic ligands containing several electron-donating atoms. Previously, we studied the neptunium(V) complexes with anions of pyridinecarboxylic acids, polypyridines, and found that the Np ion coordinates the oxygen and nitrogen atoms of heterocyclic ligands to form stable chelate rings [1‐3]. As is known, neptunium(V) in weak acid and basic aqueous solutions forms stable complexes with aliphatic polyaminoacetic acids (complexones). The compositions and stability constants were determined for the Np complexes with the anions of the following acids: iminodiacetic (H 2 ida), N -methyliminodiacetic (H 2 mida), ethylenediaminetetraacetic (H 4 edta), diethylenetetraminepentaacetic, and N -hydroxyethyliminodiacetic. It was noted that the complexes of pentavalent actinides in solutions are less stable than the complexes of hexavalent actinides with the same ligands [4‐6]. However, only neptunium(V) ethylenediaminetet

First Structural Evidence of Actinide-Nitrite Coordination

The first nitrite complex of actinide metal, {C(NH 2)3}2[NpO 2(NO 2)(Pic)2], was synthesized, and its crystal structure was determined using X-ray diffractometry and confirmed by NIR and IR spectroscopies. Main crystallographic data: space group P1, triclinic, a = 8.9329(1) A, b = 11.6669(2) A, c = 11.6698(2) A, alpha = 68.080(1) degrees, beta = 88.213(1) degrees, gamma = 73.254(1) degrees, V = 1076.45(3) A (3), and Z = 2.

Synthesis and Crystal Structure of Diaqua(2,2"-Dipyridyl)isothiocyanatoneptunoyl Monohydrate [NpO2(C10H8N2)(NCS)(H2O)2] · H2O

AbstractThe crystal structure of the complex [NpO2(C10H8N2)(NCS)(H2O)2] · H2O is determined. The unit cell parameters are a= 7.406, b= 9.517, c= 11.518 Å, α = 103.65°, β = 92.68°, γ = 96.53°, V= 781.6 Å3, space group

Tetramethylammonium Neptunium(IV) Isothiocyanate [N(CH3)4]4[Np(NCS)8]

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