Search

Uranyl complex dissolved in room-temperature ionic liquids has diagnostic absorption and emission spectra that has allowed the identification of the symmetry and geometry of the complex. The uranyl complexes are examined in imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids.

The syntheses, structures and spectroscopic properties of the two new rare-earth metal halide ortho-oxomolybdates YF[Mo[O.sub.4]] and YCl[Mo[O.sub.4]] are reported. Both structures were found to contain [[Y.sub.2][X.sub.2]].sup.4+] units in the shape of planar rhombuses, while the [Eu.sup.3+]-doped fluoride derivatives exhibited red luminescence.

The ferrocene-derivatives bis(ferrocenyl-ethynyl)-1,10-phenanthroline ([Fc.sub.2]phen) and ferrocenoyltrifluoroacetone (Hilta) is used to synthesize ferrocene-containing rate earth beta-diketonate complexes. It is found that the presence of the ferrocene groups makes the rare-earth complexes hydrophobic and well-soluble in apolar organic solvents.

The unique absorption properties of the 9-hydroxyphenalen-1-one (HPHN) ligand are explored to obtain visible-light-sensitizable rare-earth complexes in 1:3 and 1:4 metal-to-ligand ratios. The X-ray crystal structures of the tris complexes have shown solvent coordination to the central rare-earth ion, whereas in the tetrakis complexes, the four [PHN.sup.-] ligands form a protective shield around the central ion, preventing small solvent molecules from coordinating to the rare-earth ion, at least in the solid state.

The complex structural chemistry of rare-earth quinolinates is explored in the study. Most synthetic methods to obtain rare-earth quinolinates yield a mixture of different species.

The description of the structural and thermal behavior of all the members of the homologous series of neodymium(III) alkanoates, which range from neodymium(III) butyrate to neodymium(III) eicosanoate is presented. The results obtained using a single-crystal X-ray diffraction study indicates the presence of two crystallographically different neodymium ions, both having coordination numbers 9 and a geometry, which can be considered as a distorted monocapped antiprism.

The thermochemical behavior of low-temperature oxidation in fine UO 2 powders has been investigated by simultaneous thermogravimetric analysis and differential scanning calorimetry. The evaluation of the thermochemical and kinetic data reveals a complex interplay between different mechanisms. The initial reaction concerns the rapid chemisorption of oxygen gas onto the surface of UO 2 grains, having an activation energy of only 13.1 ± 0.6 kJ mol -1 . The subsequent oxidation at temperatures between 40 and 100 °C occurs first at the surface via a field-assisted mechanism, which progresses via domain growth into the bulk. At more elevated temperatures, thermally activated diffusion becomes the dominant mechanism.

Polycrystalline U 3 O 7 powder was synthesized by oxidation of UO 2 powder under controlled conditions using in situ thermal analysis, and by heat treatment in a tubular furnace. The O/U ratio of the U 3 O 7 phase was measured as 2.34 ± 0.01. The crystal structure was assessed from X-ray diffraction (XRD) and selected-area electron diffraction (SAED) data. Similar to U 4 O 9-ε (more precisely U 64 O 143 ), U 3 O 7 exhibits a long-range ordered structure, which is closely related to the fluorite-type arrangement of UO 2 . Cations remain arranged identical to that in the fluorite structure, and excess anions form distorted cuboctahedral oxygen clusters, which periodically replace the fluorite anion arrangement. The structure can be described in an expanded unit cell containing 15 fluorite-like subcells (U 15 O 35 ), and spanned by basis vectors A = a p - 2b p , B = -2a p + b p , and C = 3c p (lattice parameters of the subcell are a p = b p = 538.00 ± 0.02 pm and c p = 554.90 ± 0.02 pm; c p /a p = 1.031). The arrangement of cuboctahedra in U 3 O 7 results in a layered structure, which is different from the well-known U 4 O 9-ε crystal structure.