[en] Removal of volatiles at 243 K from solutions of completely dissolved LnF${}_3$ (Ln=La-Dy and Y) and XeF${}_2$ (molar ratio 1 : 3) in anhydrous HF acidified with an excess of BF${}_3$ resulted in [Ln (XeF${}_2$)${}_3$](BF${}_4$)${}_3$ salts. Isolated solids are stable at 298 K and give similar Raman spectra. [La(XeF${}_2$)${}_3$](BF${}_4$)${}_3$ crystallizes in the monoclinic space group C2/m at 150 K. Each La atom is coordinated with three XeF${}_2$ ligands. Six F atoms provided by six bridging BF${}_4$ units, that connect the neighboring La${}^{3+}$ atoms into columns, complete the nine-fold coordination of each La atom. Chemical reactions carried out in the same way but with molar ratio LnF${}_3$:XeF${}_2$ = 1:1 yielded [Ln (XeF${}_2$)](BF${}_4$)${}_3$ salts (La - Nd). Crystal structures of La and Nd salts are isotypic and crystallize in the monoclinic space group P2${}_1$/m at 150 K (La) and 200 K (Nd). Each Ln center is coordinated by nine fluorine atoms provided by eight BF${}_4$ units and one XeF${}_2$ ligand. The BF${}_4$ groups interconnect the Ln atoms into two-dimensional layers. With molar ratio LnF${}_3$:XeF${}_2$ = 1:2 and the same synthetic approach, only La yielded [La(XeF${}_2$)${}_2$](BF${}_4$)${}_3$ salt. Prolonged pumping of [Ln (XeF${}_2$)${}_n$](BF${}_4$)${}_3$ (n=3, 2, 1) at 298 K or attempts of the isolation at 298 K resulted in products with lower content of XeF${}_2$ or in mixtures of various products. In addition to [Ln (XeF${}_2$)](BF${}_4$)${}_3$ and LnF${}_3$/BF${}_3$ products, the [Ln (XeF${}_2$)]F(BF${}_4$)${}_2$ salts (Ln=La, Nd, Sm, Eu, Tb, Dy and Y) also formed. The crystal structures of LaF(HF)(BF${}_4$)${}_2$ and LaF (BF${}_4$)${}_2$ side products were determined. (© 2021 Wiley‐VCH GmbH)

[en] The occurrence of twinning can often be related to higher symmetrical structures. Fluorides are frequently twinned due to their close relation to high symmetry structures like fluoride, tysonite or pyrochlores. The series of compounds CsLn_2F_7 is no exception. We refined the structures of the twinned compounds with Ln=Nd, Gd, Tb, Er, Yb in space group P112_1/b. An analysis of the pseudosymmetry of the resulting structures shows a highly symmetrical cation partial structure with a cation distribution similar to the one in the hexagonal Laves phase MgZn_2. Several other compounds ALn_2F_7, which have been described in the literature, show a similar cation array. The diversity of different space groups which have been reported for ALn_2F_7 compounds can be better understood using group-subgroup relationships assuming the hypothetical structure of the cation array with space group P6_3/mmc as aristotype. Furthermore, the twinning is easily understood on the basis of the lost symmetry operations in the symmetry reduction from point group 6/mmm, e.g. to 2/m in the case of the CsLn_2F_7 compounds.

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[en] The diffuse reflectance and photoluminescence (PL) spectra of NdI₂, SmI₂, EuI₂, DyI₂, TmI₂ and YbI₂ were measured between 225 and 12 500 nm in order to determine their 4fⁿ → 4f^n-15d¹ optical bandgaps. The results were compared with those obtained using an empirical model of the electronic structure of LnI₂. The results can be used to explain the lanthanide valency and crystalline structure changes of other lanthanide diiodides such as PrI₂. (paper)

[en] From reactions of equimolar quantities of the heavier lanthanoids (M = Gd - Lu) with the elements sulfur and iodine in fused silica ampoules (900 C, 10 d) phase-pure samples of the lanthanoid sulfide iodides MSI (M = Gd - Lu) could be prepared. Besides the already structurally determined sulfide iodides MSI with M = Gd and Dy, all samples could be characterized by means of X-ray powder diffraction and their magnetic behavior was examined. In addition a single-crystal structure refinement for HoSI was carried out (orthorhombic, Pmmn; a = 415.09(4) pm, b = 531.34(5) pm, c = 920.53(9) pm), which confirmed the isotypy of the later lanthanoid sulfide iodides with the structure of FeOCl. On the basis of the X-ray powder diffraction experiments all prepared compounds could be indexed in a primitive orthorhombic unit cell. An analysis of the determined lattice parameters and cell volumes resulted in the typical lanthanoid contraction for compounds within the row of the 4f elements. The magnetochemical studies led to the expected effective magnetic moments for trivalent lanthanoid cations without showing any magnetic ordering phenomenon. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] An easy to use and rapid procedure of ionometric determination of Zn and Cd in some alloys is presented. The method is based on the different capacity of complex formation of metal cations. Ion-selective electrodes with tetradecylammonium chloride and iodide were used as indicator electrodes. To separate Zn and Cd and to increase the selectivity of determination a sorption column with strong acid cationite KU-2 is used. Zinc and cadmium determination in alloys was conducted with the help of the restricting solutions method. It was achieved by a successive measuring of the ion-selective electrode potential in a standard solution with a lower zinc (cadmium) concentration, then in eluate and in a standard solution with a higher zinc (cadmium) concentration. The procedure thus proposed provides 4 -6 determination per hour

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No abstract available

[en] The adiabatic potential energy curves and the static dipole moment curves of the low-lying singlet and triplet electronic states in the representation ^2s+1Λ^(+/−) of the five alkali chloride molecules (LiCl, NaCl, KCl, RbCl and CsCl) have been investigated via ab initio calculations using the state averaged complete active space self consistent field followed by the Multi-reference single and double configuration interaction method with Davidson correction CASSCF/(MRCI + Q). For the molecules under consideration, the spectroscopic constants T _e, R _e, ω _e and B _e, the dipole moment μ _e, and the dissociation energy D _e have been calculated for the bound states along with the percentage ionic character f _ionic around the equilibrium position of the ground state. Moreover, the transition dipole moment curves of the X¹∑⁺–(2)¹∑⁺ and X¹∑⁺–(1)¹Π transitions have been investigated for the five alkali chloride molecules. A rovibrational calculation was carried out using the canonical functions approach in order to determine the rovibrational constants E _v, B _v and D _v and the abscissas of the turning points R _min and R _max for the investigated bound states. (paper)

[en] We report a method for preparing uranium trichloride, UCl₃, by reacting ZnCl₂ with U in a molten LiCl-KCl eutectic salt at 500 °C. Cyclic voltammetry indicated the formation of UCl₃ as the reaction proceeded. After 30 h, the reaction was terminated and the final product was confirmed to contain 13.2 wt% UCl₃-LiCl-KCl salt by the ICP-OES method. (author)