Phase equilibria in the Ba2Na3[B3O6]2F-BaF2 system

The phase equilibria in the Ba₂Na₃[B₃O₆]₂F-BaF₂ section, which belongs to the ternary mutual Ba, Na//BO₂,F system, have been studied by the methods of solid-phase synthesis, visual polythermal analysis, and differential-thermal analyses. It is shown that this section can be used to grow bulk Ba₂Na₃[B₃O₆]₂F crystals.     

Phase equilibria and growth of β-BaB2O4 crystals in the BaB2O4-Ba2Na3[B3O6]2F system

A complex investigation of the BaB₂O₄-Ba₂Na₃[B₃O₆]₂F cut, which belongs to the ternary mutual Ba, Na//BO₂, F (BaB₂O₄-(NaBO₂)₂-(NaF)₂-BaF2) system, has been performed. The cut is quasibinary, with the following eutectics coordinates: 810 ± 5°C, 85 mol % Ba₂Na₃[B₃O₆]₂F, 15 mol % BaB₂O₄. It is shown that this system can be used to grow bulk β-BaB₂O₄ crystals.     

Synthesis and crystal structure of (NH4)3[UO2(CH3COO)3]2[UO2(CH3COO)(NCS)2(H2O)]

Single crystals of the compound (NH₄)₃[UO₂(CH₃COO)₃]₂[UO₂(CH₃COO)(NCS)₂(H₂O)] (I) are synthesized, and their structure is investigated using X-ray diffraction. Compound I crystallizes in the monoclinic system with the unit cell parameters a = 18.3414(6) ?, b = 16.3858(7) ?, c = 12.4183(5) ?, β = 92.992(1)°, space group C2/c, Z = 4, V = 3727.1(3) ?³, and R = 0.0253. The uranium-containing structural units of crystals I are mononuclear complexes of two types with an island structure, i.e., the [UO₂(CH₃COO)₃]⁻ anionic complexes belonging to the crystal-chemical group (AB ₃⁰¹ = UO₂²⁺, B ⁰¹ = CH₃COO⁻) of the uranyl complexes and the [UO₂(CH₃COO)(NCS)₂(H₂O)]⁻ anionic complexes belonging to the crystal-chemical group AB ⁰¹M₃¹ (A = UO₂²⁺, B ⁰¹ = CH₃COO⁻, M ¹ = NCS⁻ or H₂O).     

Crystal structure and phase transitions in the new crystals of [(CH3)2NH2]2CuCl4[(CH3)2NH2]Cl

Crystals grown from a solution of dimethylammonium and copper chlorides are studied using electron paramagnetic resonance (EPR) and X-ray diffraction. The dielectric properties of the crystals grown are measured. It is established that the crystals have the composition [(CH₃)₂NH₂]₂CuCl₄[(CH₃)₂NH₂]Cl and, in phase I at room temperature, are described by the orthorhombic space group Pna2₁ with the unit cell parameters a = 11.338 Å, b = 9.981 Å, and c = 15.675 Å. At temperatures of 279 K and 253 K, the crystals undergo jumpwise phase transitions into the incommensurate modulated ferroelectric phase II and commensurate modulated phase III, respectively. __________ Translated from Kristallografiya, Vol. 49, No. 1, 2004, pp. 92–100. Original Russian Text Copyright ? 2004 by Kirpichnikova, Pietraszko, Bednarski, Waplak, Sheleg. Dedicated to the 80th Birthday of L.A. Shuvalov     

Glass formation in the MoO3–Nd2O3–La2O3–B2O3 system

In MoO₃–Nd₂O₃–B₂O₃ and MoO₃–Nd₂O₃–La₂O₃–B₂O₃ systems, glasses were obtained in the region between 20 and 30 mol% Ln₂O₃. A liquid-phase separation region was observed near the MoO₃–B₂O₃ side up to 20 mol% Ln₂O₃ (La, Nd). The amorphous phases were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), UV–VIS and infrared spectroscopy (IR). According to DTA data B₂O₃-rich glasses are stable up to 630 °C while glasses rich in MoO₃ are stable up to 430 °C. The glasses are transparent in the visible region. Structural models for the glasses network were suggested on the basis of IR spectral investigations. It was established that BO₃ (1380 cm⁻¹), BO₄ (1100–950 cm⁻¹) and MoO₄ (860 cm⁻¹) groups build up the glass network. MoO₆ units (band at 880 cm⁻¹) together with BO₃ units participate in the formation of the glass network with a high MoO₃ content (80–90 mol%).     

Crystal structure of R[UO2(CH3COO)3] (R = NH 4+ , K+, or Cs+)

The single crystal structure of NH₄[UO₂(CH₃COO)₃] (I), K[UO₂(CH₃COO)₃] (II), and Cs[UO₂(CH₃COO)₃] (III) is studied by X-ray diffraction. I and II crystallize in the tetragonal crystal system. The crystal data are as follows: a = 13.6985(3) and c = 27.5678(14) ?, V = 5173.1(3) ?³, space group I4₁/a, Z = 16, and R = 0.023 for I; a = 13.8890(5) and c = 26.0839(18) ?, V = 5031.7(4) ?³, space group I4₁/a, Z = 16, and R = 0.037 for II. Crystals III are orthorhombic, a = 18.176(2), b = 13.119(2), and c = 22.088(4) ?, V = 5267(1)?³, space group Pbca, Z = 16, and R = 0.0424. In structures I–III, the uranium-containing structural units are represented by discrete mononuclear [UO₂(CH₃COO)₃]⁻ groups, which belong to the AB ₃⁰¹ (A = UO₂²⁺, B ⁰¹=CH₃COO⁻) crystal chemical group of uranyl complexes.     

Crystal structure of M4[(UO2)2C2O4(SO4)2(NCS)2] ( M = K+, Rh+) and K4[(UO2)2C2O4(SeO4)2(NCS)2]

Three heteroacidoligand uranyl complexes M ₄[(UO₂)₂C₂O₄(SO₄)₂(NCS)₂] (M = K⁺ (I), Rb⁺ (II)) and K₄[(UO₂)₂C₂O₄(SeO₄)₂(NCS)₂] (III) have been synthesized and their crystal structure has been determined by X-ray diffraction analysis. The compounds I–III are isostructural and crystallized in the monoclinic system, sp. gr. P2₁/c, Z = 2, a = 11.5548(3) ?, b = 7.0847(1) ?, c = 13.5172(3) ?, β = 93.130(1)°, V = 1104.90(4), R = 0.015 (I); a = 11.5854(9) ?, b = 7.3841(6) ?, c = 13.9072(9) ?, β = 95.754(3)°, V = 1183.74(15), R = 0.0235 (II); a = 11.6715(3) ?, b = 7.1418(2) ?, c = 13.8546(1) ?, β = 93.539(1)°, V = 1152.66(5), R = 0.0126 (III). Basic structural units of these crystals are [(UO₂)₂C₂O₄(XO₄)₂(NCS)₂]⁴⁻ chains, which belong to the crystallochemical group A ₂ K ⁰² B ₂² M ₂¹ (A = UO₂²⁺, K ⁰² = C₂O₂₋⁴, B ² = SO₄²⁻ or SeO₄²⁻, M ¹ = NCS⁻) of uranyl complexes. Uranium-containing chains are connected into a 3D framework via a system of electrostatic interactions with potassium or rubidium cations from outer spheres. Original Russian Text ? I.V. Medrish, E.V. Peresypkina, A.V. Virovets, L.B. Serezhkina, 2008, published in Kristallografiya, 2008, Vol. 53, No. 3, pp. 495–498.     

Ionic conductivity of Li2OB2O3 thin films

The ionic conductivity of evaporated Li₂OB₂O₃ thin films has been studied. These thin films were found to show a considerably high ionic conductivity of 1 × 10^?7 Ω^?1 cm^?1 at room temperature. The conductivity increases with increasing Li content and exhibits a maximum value near 3Li₂O·B₂O₃. The structure of these films was determined using infrared absorption and laser Raman scattering spectroscopy. Using the results, the correlation between structure and conductivity is also discussed.     

Synthesis, spectroscopic characterisation and X-ray structure of [trans-Co(en)2(NO2)2]2(Cr2O7)

Dark red crystals of bis[trans-dinitrobis(ethylenediamine)cobalt(III)] dichromate, [trans-Co(en)₂(NO₂)₂]₂(Cr₂O₇) have been obtained by slowly allowing to mix the solutions of potassium dichromate and trans-dinitrobis(ethylenediamine)cobalt(III) nitrate in 1:2 molar ratio in aqueous medium. Elemental analyses and spectroscopic techniques (IR, UV/visible, ¹H and ¹³C NMR) were used for characterizing the complex salt. The complex salt crystallizes in the orthorhombic space group Fdd2 with unit cell dimensions a = 24.778(2) ?, b = 30.457(2) ?, c = 6.5364(5) ?, Z = 8, V = 4932.8(7) ?³, R₁ = 0.0617 and wR₂ = 0.1518. X-ray structure determination revealed an ionic structure consisting of cationic cobaltammine [trans-Co(en)₂(NO₂)₂]NO₃ and dichromate anion. It is the first crystal structure of this cation with a dianion.     

Magnetic behaviour of 20Fe2O380[3B2O3(1−χ)PbOχAs2O3] glasses

The results of magnetic measurements performed on 20Fe₂O₃80[3B₂O₃(1?χ)PbOχAs₂O₃] glasses, in the temperature range 4.2 to 300 K are reported. By decreasing the temperature a downward curvature of reciprocal susceptibility is observed for T<50 K. The composition dependence of the paramagnetic Curie temperatures and Curie constants is discussed.     

The structure of the scandium iodide complex with antipyrine (AP) and its comparison with the structure of nonisostructural analogues (Compounds [Ln(AP)6]I3 (Ln = La, Y, or Eu))

An X-ray diffraction study of the scandium iodide complex with antipyrine [Sc(AP)₆]I₃ (AP is antipyrine, i.e., 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) (I), which is not isostructural to the analogous compounds of Y, La, and Eu (II), is performed. Crystals I are trigonal; a = 24.911 ? and c = 10.140 ?; Z = 3, space group P $ \bar 3 $ \bar 3 . Crystal I is built of [Sc(AP)₆]³⁺ complex cations of two types and I⁻ anions. In both cations, the Sc atom is octahedrally coordinated by six O atoms of six AP ligands (Sc-O, 2.054–2.078 ?). Complexes I differ from II by the absence of π-π stacking interactions between AP molecules, resulting in a supramolecular cation. Complex cations I of both types form combined layers. All I⁻ anions are located in the interlayer space, being statistically disordered within a flat area limited by eight complex cations of Sc1 and Sc2.     

Short range order and glass transition in AgIAg2OB2O3 vitreous electrolytes

Several experimental techniques are used to study the short range order, the dynamics and the glass transition in AgIAg₂B₂O₃ compounds. Addition of Ag₂O to B₂O₃, up to [Ag₂O]/[B₂O₃] ?0.5 modifies the borate network by creating a BO₄ unit for each silver added. Addition of AgI decreases the glass transition temperature (T_g) but has only minor effects on the short range structure of the borate network. Silver iodide is partially accomodated in the interstices of the glass network. The relationship among a tentative structural picture, the ion transport phenomena and the low temperature dynamics are discussed.An investigation of the dynamics in the AgI·Ag₂O·2B₂O₃ glass near and above T_g is presented. With NMR techniques, we monitor the onset of tumbling of the borate units and the dynamical effects of crystallization and/or aging of the glass. Hysteresis effects in the ionic conductivity (σ) temperature dependence and the non-Arrhenian behavior of σT near T_g are interpreted in terms of structural modifications occurring at elevated temperatures in the glass.     

Crystal structure of bis[diethylenetriamine-N′-(3-propionato)-N, N′,N″,O,O′]dicopper(II) Diperchlorate, [Cu2(4-Dtmp)2](ClO4)2

A complex of copper(II) with the diethylenetriaminemonopripionate ligand [Cu₂(4-Dtmp)₂](ClO₄)₂ (I) is synthesized and characterized using X-ray diffraction. The crystals of compound I are monoclinic, a = 7.740(2) Å, b = 19.199(3) Å, c = 8.449(2) Å, β = 91.61(2)°, Z = 2, and space group P2₁/n. The structural units of crystal I are centrosymmetric dimeric cations and statistically disordered ClO ₄ ⁻ anions. In the cation, the copper atom is coordinated by three N atoms [mean Cu-N, 2.01(1) Å] and two O atoms [Cu-O, 2.134(6) Å and 1.958(7) Å] of the pentadentate bridging-chelate Dtmp ligand, which occupy vertices of the trigonal bipyramid. The binuclear cations are linked via centrosymmetric pairs of hydrogen bonds into ribbons aligned parallel to the a axis of the crystal. The ClO ₄ ⁻ anions form columns in the same direction. In the crystal, the cationic ribbons and anionic columns alternate in a chessboard fashion. __________ Translated from Kristallografiya, Vol. 50, No. 3, 2005, pp. 450–454. Original Russian Text Copyright ? 2005 by Antsyshkina, Sadikov, Poznyak, Sergienko.     

Solvothermal Syntheses and Crystal Structures of Neodymium Thiostannates [Nd(dien)3]2[(Sn2S6)Cl2] and [Nd(dien)3]2[(Sn2S6)(SH)2]

Abstract  

Two neodymium thiostannates [Nd(dien)₃]₂[(Sn₂S₆)Cl₂] (1) and [Nd(dien)₃]₂[(Sn₂S₆)(SH)₂] (2) (dien = diethylenetriamine) were synthesized by the reaction of tin and sulfur in the presence of NdCl₃ and Nd₂O₃, respectively under solvothermal conditions. Compounds 1 and 2 crystallize in monoclinic space group P2₁/n. Crystallographic data for 1: a = 11.6722(16), b = 15.119(2), c = 14.1566(19) ?, β = 96.213(3)°, V = 2483.6(6) ?³, Z = 4. For 2: a = 11.7190(14), b = 15.2168(19), c = 14.2209(18) ?, β = 95.775(4)°, V = 2523.1(5) ?³, Z = 4. The nine-coordinate [Nd(trien)₃]³⁺ complex cation formed in situ acts as the counter ion to the [Sn₂S₆]⁴⁻ anion. The [Nd(dien)₃]³⁺, [Sn₂S₆]⁴⁻ and Cl^– (or SH^–) ions form a 3-dimensional network structure through the N–H···S and N–H···Cl hydrogen bonds.     

Synthesis and X-ray diffraction study of (Cs0.5Ba0.25)[UO2(CH3COO)3] and Ba0.5[UO2(CH3COO)3]

Uranyl triacetate complexes (Cs_0.5Ba_0.25)[UO₂(CH₃COO)₃] (I) and Ba_0.5[UO₂(CH₃COO)₃] (II) are synthesized for the first time and their structures are determined by X-ray diffraction. Both compounds crystallize in the cubic crystal system. The crystal data are as follows: a = 17.3289(7) ?, V = 5203.7(4) ?³, space group I2₁3 and Z = 16 (I); a = 17.0515(8)?, V = 4957.8(4) ?³, space group I $ \bar 4 $ \bar 4 3d, and Z = 16 (II). In I and II, as in all uranyl triacetates studied earlier, the coordination polyhedron of the uranium atom is a hexagonal bipyramid whose vertices are occupied by the oxygen atoms of the uranyl and three acetate groups. The uranium-containing group belongs to the AB ₃⁰¹ (A = UO₂²⁺, B ⁰¹ = CH₃COO⁻) crystal chemical group of uranyl complexes. It was found that compound II is isostructural to the (Rb_0.50Ba_0.25)[UO₂(CH₃COO)₃] studied earlier.     

Synthesis, structure and supramolecular assembly in the crystalline state of a bifunctionalized arylimido derivative of hexamolybdate [n-Bu4N]2[Mo6O17(o,p-(MeO)2C6H3N)2]

A novel bifunctionalized arylimido derivative of hexamolybdate [n-Bu₄N]₂[Mo₆O₁₇(o,p-(MeO)₂C₆H₃N)₂] (1) was synthesized by self-assembled metathesis of α-type octamolybdate ion and 2,4-dimethoxyaniline and structurally characterized by crystal X-ray diffraction. Crystallographic data for1: monoclinic system, space group:C2/c,a = 17.319(4),b = 18.087(4),c = 21.357(5) ?, β = 106.486(4),V = 6415(2) ?³, andZ = 4,D_c = 1.693 g/cm³,R₁ = 0.0439. The complex has a short Mo–N bond length of 1.735(5) ? and an imido (Mo–N–C) bond angle of 177.8(4)^∘. The complex has also been characterized by¹H NMR, IR, and UV–vis spectroscopy.     

Nuclear magnetic resonance studies of the glasses in the system Na2OB2O3SiO2

The ¹¹B NMR spectra have been used to study the structure of glasses in the system Na₂OB₂O₃SiO₂. The fraction of BO₄ units, and the fraction of BO₃ units with one or two nonbridging oxygens, are measured and analyzed according to a structural model. The results indicate that: (1) for a sodium oxide to boron oxide ratio of 0.5 or less, the Na⁺¹ ions are attracted primarily by the borate network; therefore, the ternary glasses can be viewed as binary sodium borate glasses diluted by SiO₂; (2) when the sodium oxide to boron oxide ratio exceeds 0.5, the additional Na₂O results in the formation of [BSi₄O₁₀]^?1 units at the expense of diborate and SiO₄ units. In this process, Na⁺¹ ions are still taken up only by the borate network. After all the available SiO₄ units are consumed to form [BSi₄O₁₀]^?1 units, additional Na⁺¹ ions are proportionally shared between the borate and silicate networks.     

New oxygen-and lead-deficient lead borate Pb 0.9 (I) Pb 0.6 (II) [BO2.25]2 = 2Pb0.75[BO2.25] and its relation to aragonite and calcite structures

Anhydrous oxygen-and lead-deficient lead borate of the composition Pb _0.9 ^(I) Pb _0.6 ^(II) [BO_2.25]₂ = 2Pb_0.75[BO_2.25] (sp. gr. P312) has been obtained by the hydrothermal synthesis. New acentric borate possesses optical nonlinearity comparable with the optical nonlinearity of α-quartz. The crystal structure of new borate is determined and refined by two X-ray diffraction methods—the single crystal diffractometry and the full-profile analysis. All the positions in the structure, except for those of the boron atom in the triangular coordination, are occupied only partly; one of the two lead positions is split. It is established that new borate is closely related to calcium carbonates—aragonite, calcite, and paralstonite. With an increase of the temperature, new borate undergoes the reversible phase transition into the centrosymmetric, most probably, aragonite-like phase.     

Structure of diaqua(itaconato) cadmium(II), [Cd(C5H4O4)(OH2)2]

[Cd(C₅H₄O₄)(OH₂)₂] (1), crystallizes in the monoclinic system, space groupP2₁/n, with lattice parametersa=7.323(2),b=16.028(6),c=7.202(2) Å, β=113.11(1)°, andZ=4. The Cd atom coordinates to seven oxygens in a monocapped trigonal antiprism fashion. The antiprisms share one vertex to form chains which run approximately parallel to thec axis. The itaconate ligands link the chains to form layers which stack along theb axis.     

Synthesis and X-ray structural investigation of K2(H5O2)[UO2(C2O4)2(HSeO3)]

The synthesis and X-ray diffraction analysis of K₂(H₅O₂)[UO₂(C₂O₄)₂(HSeO₃)] single crystals have been performed. This compound crystallizes in the triclinic system with the unit-cell parameters a = 6.7665(4) ?, b = 8.8850(4) ?, c = 12.3147(7) ?, α = 94.73°, β = 90.16°, γ = 92.11°, sp. gr. P[`1]P\bar 1, Z = 2, and R = 0.019. The basic structural units are island [UO₂(C₂O₄)₂(HSeO₃)]³⁻ groups, which belong to the AB ₂⁰¹ M ¹ crystallochemical group of uranyl complexes (A = UO₂²⁺, B ⁰¹ = C₂O₄²⁻, and M ₁ = HSeO₃⁻). Uraniumcontaining complexes are linked through K⁺ and H₅O₂⁺ ions and via a system of hydrogen bonds with the participation of oxonium hydrogen atoms in this structure.