Synthesis and crystal structures of M2[(UO2)3(SeO4)5](H2O)16 (M=Co, Zn)

Krivovichev, Sergey V.; Kahlenberg, Volker

doi:10.1016/j.jallcom.2004.11.028

Cited by 28 publications

(7 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hereby the Se4 position would be occupied by 100%, and hence the structural unit would be [(NpO 2 ) 3 (SeO 4 ) 5 ] 4− . Such layers and topologies can for example be found in M 2 [(UO 2 ) 3 -(SeO 4 ) 5 ](H 2 O) 16 (M = Co, Zn) 43 and Na 6 [(Np V O 2 ) 2 -(Np VI O 2 )(MoO 4 ) 5 ](H 2 O) 13 . 44 In this case the structure would likely not be a quasi-double sheet structure but a structure made up of monolayers.…”

Section: ■ Resultsmentioning

confidence: 99%

Unexpected Behavior of Np in Oxo-selenate/Oxo-selenite Systems

et al. 2018

View full text Add to dashboard Cite

A study of neptunium (Np) chemistry in the complex oxo-selenium system has been performed. Hereby, two sets of precipitation experiments were conducted, investigating the influence of the initial oxidation state of selenium using SeO and HSeO with Np in alkali nitrate solution, keeping the ratio of Np/Se constant. Surprising results were observed. Five novel neptunium and selenium bearing compounds have been obtained by slow evaporation from aqueous solution. The novel Np phase K[Np(SeO)(HSeO)]·(HO) (1) crystallizes in green-colored, plate-shaped crystals and was obtained by adding SeO and ANO to a Np stock solution. Single-crystal X-ray diffraction reveals one-dimensional chain structures composed of square antiprismatic NpO polyhedra linked via four trigonal pyramidal SeO and HSeO units. Raman spectral analysis supports the presence of both selenite and hydroselenite due to the presence of corresponding modes within the spectra. The addition of selenic acid to a Np stock solution resulted in the precipitation of elongated rose prisms of K[(NpO)(SeO)(HO)]·(HO) (2), Rb[(NpO)(SeO)(HO)]·(HO) (3) and K[(NpO)(SeO)(HO)]·(HO) (4) as well as light red plates of Cs[(NpO)(SeO)] (5). To our knowledge, this is the first report of Np selenates. All four structures show two-dimensional layered structures with alkali cations acting as charge balancing counter cations. Hereby the layers of compounds 2 and 3 are found to be orientational geometric isomers. Distinctly different phenomena are made responsible for the phase formation within these systems. The kinetically driven process of Np disproportionation led to the formation of the Np selenites in the Se-based system, whereas the oxidation of Np by reduction of nitrate in acidic conditions is responsible for the formation of the Np selenates in the Se system. The influence of air oxygen is also discussed for the latter reaction.

show abstract

Section: ■ Resultsmentioning

confidence: 99%

Unexpected Behavior of Np in Oxo-selenate/Oxo-selenite Systems

et al. 2018

View full text Add to dashboard Cite

show abstract

“…For example, high energy X-ray scattering (HEXS) studies on UO 2 2+ –sulfate and −selenate ion pairs in aqueous solutions suggested that uranyl to sulfate-ion orientation appears rigid and uranyl selenate ion pairs appear to rotate freely. − This behavior may help to explain the rotational disordering of the selenate group in 3 , while the sulfate group in 5 is ordered. In fact, there are more reported examples of actinyl compounds with disordered selenate anions, such as α-Mg 2 (UO 2 ) 3 (SeO 4 ) 5 (H 2 O) 16 and M 2 (UO 2 ) 3 (SeO 4 ) 5 (H 2 O) 16 (M = Co, Zn). , Sulfate anions generally bind to actinyl cations in both monodentate and bidentate modes, while selenate ligands connect to actinyl units predominantly in a monodentate mode . This can be understood from the steric repulsion between the center atoms in the ligand and actinyl groups.…”

Section: Discussionmentioning

confidence: 99%

Three New Sodium Neptunyl(V) Selenate Hydrates: Structures, Raman Spectroscopy, and Magnetism

2012

View full text Add to dashboard Cite

Green crystals of Na(NpO(2))(SeO(4))(H(2)O) (1), Na(3)(NpO(2))(SeO(4))(2)(H(2)O) (2), and Na(3)(NpO(2))(SeO(4))(2)(H(2)O)(2) (3) have been prepared by a hydrothermal method for 1 or evaporation from aqueous solutions for 2 and 3. The structures of these compounds have been characterized by single-crystal X-ray diffraction. Compound 1 is isostructural with Na(NpO(2))(SO(4))(H(2)O) (4). The structure of 1 consists of ribbons of neptunyl(V) pentagonal bipyramids, which are decorated and further connected by selenate tetrahedra to form a three-dimensional framework. The resulting open channels are filled by Na(+) cations and H(2)O molecules. Within the ribbon, each neptunyl polyhedron shares corners with each other solely through cation-cation interactions (CCIs). The structure of 2 adopts one-dimensional [(NpO(2))(SeO(4))(2)(H(2)O)](3-) chains connected by Na(+) cations. Each NpO(2)(+) cation is coordinated by four monodentate SeO(4)(2-) anions and one H(2)O molecule to form a pentagonal bipyramid. The structure of 3 is constructed by one-dimensional [(NpO(2))(SeO(4))(2)](3-) chains separated by Na(+) cations and H(2)O molecules. These chains have two configurations resulting in two disordered orientations of the Se(2)O(4)(2-) tetrahedra. Each NpO(2)(+) cation is coordinated by one bidentate Se(1)O(4)(2-) and three monodentate Se(2)O(4)(2-) anions to form a pentagonal bipyramid. Raman spectra of 1, 2, and 4 were collected on powder samples. For 1 and 4, the neptunyl symmetric stretch modes (670, 676, 730, and 739 cm(-1)) shift significantly toward lower frequencies compared to that in 2 (773 cm(-1)), and there are several asymmetric neptunyl stretch bands in the region of 760-820 cm(-1). Magnetic measurements obtained from crushed crystals of 1 are consistent with a ferromagnetic ordering of the neptunyl(V) spins at 6.5(2) K, with an average low temperature saturation moment of 2.2(1) μ(B) per Np. Well above the ordering temperature, the susceptibility follows Curie-Weiss behavior, with an average effective moment of 3.65(10) μ(B) per Np and a Weiss constant of 14(1) K. Correlations between lattice dimensionality and magnetic behavior are discussed.

show abstract

“…The diversity of polyhedral units found in uranyl compounds is unique, starting from isolated complexes [1][2][3] and clusters [4][5][6][7] to cage compounds [8][9][10][11] and nanotubules [12][13][14]. Selenium-containing uranyl oxysalts are known for both monoand divalent inorganic cations [15][16][17][18][19], as well as for organic template molecules of various charge and structure [20][21][22][23][24]. The crystal structures of uranyl selenates and selenites are based upon a variety of complex units formed by polymerization of U and Se coordination polyhedra.…”

Section: Introductionmentioning

confidence: 99%

Topologically and geometrically flexible structural units in seven new organically templated uranyl selenates and selenite–selenates

Gurzhiy

Kovrugin

Tyumentseva

et al. 2015

Journal of Solid State Chemistry

Self Cite

View full text Add to dashboard Cite

a b s t r a c tSingle crystals of seven novel uranyl oxysalts of selenium with protonated methylamine molecules, [C 2 Their crystal structures have been solved by direct methods and their uranyl selenate and selenite-selenate units investigated using black-and-white graphs from the viewpoints of topology of interpolyhedral linkages and isomeric variations. The crystal structure of IV is based upon complex layers with unique topology, which has not been observed previously in uranyl selenates. Investigations of the statistics and local distribution of the U-O br -Se bond angles demonstrates that shorter angles associate with undulations, whereas larger angles correspond to planar areas of the uranyl selenite layers.

show abstract

Synthesis and crystal structures of M2[(UO2)3(SeO4)5](H2O)16 (M=Co, Zn)

Cited by 28 publications

References 21 publications

Unexpected Behavior of Np in Oxo-selenate/Oxo-selenite Systems

Unexpected Behavior of Np in Oxo-selenate/Oxo-selenite Systems

Three New Sodium Neptunyl(V) Selenate Hydrates: Structures, Raman Spectroscopy, and Magnetism

Topologically and geometrically flexible structural units in seven new organically templated uranyl selenates and selenite–selenates

Contact Info

Product

Resources

About