Pb(18‐crown‐6)Cl2 and Hg(18‐crown‐6)I2: Molecular Dihalides Trapped in a Crown Ether

Pb(18‐crown‐6)Cl₂ and Hg(18‐crown‐6)I₂ are obtained as transparent colourless crystals of needle and hexagonal shape, respectively, by isothermal evaporation of their dichloromethane solutions. Pb(18‐crown‐6)Cl₂ crystallizes with the trigonal crystal system [ , no. 148, a = b = 1176.3(2), c = 1191.8(3) pm, V = 1428.2(5) 10⁶·pm³, Z = 3] whereas Hg(18‐crown‐6)I₂ crystallizes with the orthorhombic crystal system (Pnma, no. 62, a = 1613.9(2) pm, b = 2822.2(5) pm, c = 841.3(1) pm, V = 3832(1)10⁶·pm³, Z = 8). Both compounds are characterized by linear MX₂ (HgI₂ or PbCl₂) molecular units which are encrypted by the crown ether. In both cases, the divalent metal ion resides in the middle of the crown ether resulting in a hexagonal bipyramidal coordination environment for the metal cations. The molecular symmetry comes close to D_3d. Hg(18‐crown‐6)I₂ and Pb(18‐crown‐6)Cl₂ differ in the way the single MX₂@18‐crown‐6 units are packed. Whereas the Hg(18‐crown‐6)I₂ molecules are arranged in a (distorted) cubic closest packing, the Pb(18‐crown‐6)Cl₂ molecules adopt a hexagonal closest packing.     

Rhenium chelate complexes with maltolate or kojate

Novel rhenium complexes containing the maltolate (mal) or kojate (koj) anions as chelating ligands have been synthesized: [ReOCl(mal)₂] (1), [ReOCl₂(mal)(PPh₃)] (2), [ReOBr₂(mal)(PPh₃)] (3), [ReOCl₂(koj)(PPh₃)] (4) and [ReOBr₂(koj)(PPh₃)] (5). The products have been characterized by FTIR, ¹H, ¹³C, and ³¹P NMR spectroscopies and elemental analysis. The crystal and molecular structures of all complexes were determined. Complex 1 crystallizes monoclinic, space group C2/c, Z = 8. It contains two O,O′-bidentate maltolate ligands and one chloro ligand at the (ReO)³⁺ unit, so that a distorted octahedral geometry is adopted by the six-coordinated rhenium(V) center. The chloro ligand occupies a cis position to the oxo ligand. Complexes 2 and 3 are isostructural and crystallize orthorhombic, space group Pbca and Z = 8. The isostructural complexes 4 and 5 crystallize monoclinic, space group P2₁/n and Z = 4. In complexes 2–5, the (ReO)³⁺ unit is coordinated by a monoanionic O,O-bidentate unit of the maltolate (2 and 3) or kojate (4 and 5) ligand, one triphenylphosphine and two halogeno ligands (Cl in 2 and 4; Br in 3 and 5), with the rhenium(V) center in a distorted octahedral environment. The halide ligands are in cis positions to each other.     

Turn-on Circularly Polarized Luminescence in Chiral Indium Chlorides by 5s2 Metal Centers

Introducing chirality into the metal-halide hybrids has enabled many emerging properties including chiroptical activity, spin-dependent transport, and ferroelectricity. However, most of the chiral metal-halide hybrids to date are non-emissive, and the underlying mechanism remains elusive. Here, we show a new strategy to turn on the circularly polarized luminescence (CPL) in chiral metal-halide hybrids. We demonstrate that alloying Sb³⁺ into chiral indium-chloride hybrids dramatically increases the photoluminescence quantum yield in two new series of chiral indium-antimony chlorides. These materials exhibit strong CPL signals with tunable energy and a high dissymmetry factor up to 1.5×10⁻². Mechanistic studies reveal that the emission originates from the self-trapped excitons centered in 5s² Sb³⁺. Moreover, near-ultraviolet pumped white light is demonstrated with a polarization up to 6.0 %. Our work demonstrates new strategies towards highly luminescent chiral metal-halide hybrids.     

Synthetic Receptors with Micromolar Affinity for Chloride in Water

A water-soluble coordination cage was obtained by reaction of Pd(NO₃)₂ with a 1,3-di(pyridin-3-yl)benzene ligand featuring a short PEG chain. The cavity of the metal-organic cage contains one nitrate anion, which is readily replaced by chloride. The apparent association constant for chloride binding in buffered aqueous solution is K_a=1.8(±0.1)×10⁵ M⁻¹. This value is significantly higher than what has been reported for other macrocyclic chloride receptors. The heavier halides Br⁻ and I⁻ compete with binding or self-assembly, but the receptor displays very good selectivity over common anions such as phosphate, acetate, carbonate, and sulfate. A further increase of the chloride binding affinity by a factor of 3 was achieved using a fluorinated dipyridyl ligand.     

Interference-free determination of thallium in aqua regia leaches from rocks, soils and sediments by D(2)-ETAAS method using mixed palladium-citric acid-lithium chemical modifier

The mixture of palladium (chloride) with citric acid and lithium is proposed as a new chemical modifier for the elimination of interference occurred during the determination of Tl in aqua regia extracts from rocks, soils and sediments by electrothermal atomic absorption spectrometry using instrumentation with deuterium-lamp background correction (D₂-ETAAS). Palladium was preferred to rhodium and platinum as to analyte stabilization, citric acid served as an effective reducing agent facilitating formation of Pd-Tl stable covalent bonds playing an important role in the analyte stabilization. Citric acid in addition helps to remove most of interfering chloride at low temperature. The further addition of Li increased significantly the robustness of chemical modifier against strongly interfering ZnCl₂ matrix by binding free chlorine into a more stable LiCl molecule. In the presence of the proposed chemical modifier the temperature for the final step of pyrolysis was adjustable up to 1000 °C, without any noticeable loss of volatile Tl species and the interference of the rest chloride matrix was significantly reduced. The application of the modifier to direct determination of Tl in aqua regia extracts from rocks, soils and sediments has ensured the characteristic mass and LOD value for the original sample 13 pg and 0.043 μg g⁻¹, respectively (10-μL aliquots of sample) and has enabled the use of matrix-free standard solutions for attaining accurate analysis. The accuracy was verified by the analysis of certified reference samples and by the comparison of results with those found by an inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (ICP-oa-TOFMS) method.     

高分子载体四氯化锡复合物催化剂(Ⅱ)——苯乙烯、甲基丙烯酸甲酯共聚物-四氯化锡复合物

高分子载体催化剂的研究和开发日益受到重视。四氯化锡是一种常用的强Iewis酸,在空气中强烈水解而产生大量盐酸烟雾,保存和使用都不方便,我们曾将四氯化锡与聚苯乙烯交联白球反应制成了一种高分子载体催化剂,对酯化、缩醛、缩酮等有机反应有良好的催化性能,但它在反应中洗脱流失严重,重复使用性能很差,基本上是十种高分子保护型的载体催化剂。为了改善其稳定性,从而提高重复使用性能,我们合成了含有富电子基团的新高分子载体,使四氯化锡与载体中的富电子基团形成较稳定的复合物,使之既保持良好的催     

新型含磷无机离子交换剂研究(Ⅵ)——非晶态交换剂六偏磷酸锡的结构分析

通过大角度X射线散射分析,求出了新型无机离子交换剂六偏磷酸锡的径向分布函数,推断其化学结构。应用此结构较好地解释了交换剂的离子交换性质。     

Pr4S3[Si2O7] und Pr3Cl3[Si2O7]: Durch weiche Fremdanionen modifizierte Derivate von Praseodymdisilicat

Pr₄S₃[Si₂O₇] and Pr₃Cl₃[Si₂O₇]: Derivatives of Praseodymium Disilicate Modified by Soft Foreign Anions For synthesizing both the disilicate derivatives Pr₄S₃[Si₂O₇] and Pr₃Cl₃[Si₂O₇], Pr, Pr₆O₁₁ and SiO₂ are brought to reaction with S and PrCl₃, respectively, in suitable molar ratios (850 °C, 7 d) in evacuated silica tubes. By using NaCl as a flux, Pr₄S₃[Si₂O₇] crystallizes as pale green, transparent single crystals (tetragonal, I4₁/amd, a = 1201.6(1), c = 1412.0(2) pm, Z = 8) with the appearance of slightly compressed octahedra. On the other hand, Pr₃Cl₃[Si₂O₇] emerges as pale green, transparent platelets and crystallizes monoclinically (space group: P2₁, a = 530.96(6), b = 1200.2(1), c = 783.11(8) pm, β = 109.07(1)°, Z = 2). In both crystal structures ecliptically conformed [Si₂O₇]^6– units of two corner‐linked [SiO₄] tetrahedra with Si–O–Si bridging angles of 131° in the sulfide and 148° in the chloride disilicate are present. In Pr₄S₃[Si₂O₇] both crystallographically independent Pr³⁺ cations show coordination numbers of 8 + 1 (5 S^2– and 3 + 1 O^2–) and 9 (3 S^2– and 6 O^2–). For Pr1, Pr2 and Pr3 in Pr₃Cl₃[Si₂O₇] coordination numbers of 10 (5 Cl^– and 5 O^2–) and 9 (2 ×; 4 Cl^– and 5 O^2– or 3 Cl^– and 6 O^2–, respectively) occur.     

Pr(BO2)3 und PrCl(BO2)2: Zwei meta‐Borate des Praseodyms im Vergleich

Pr(BO₂)₃ and PrCl(BO₂)₂: Two Praseodymium meta‐Borates in Comparison Single‐crystalline PrCl(BO₂)₂ can be obtained by the reaction of praseodymium, Pr₆O₁₁ and PrCl₃ with a small excess of B₂O₃ in evacuated silica tubes after seven days at 850 °C. If NaCl is additionally used as flux, single crystals of Pr(BO₂)₃ dominate the main product. Both praseodymium(III) meta‐borates are air and water stable. The crystals of PrCl(BO₂)₂ emerge as long, thin, pale green needles which tend to severe twinning due to their fibrous habit. The crystal structure (triclinic, P1¯; a = 420.56(4), b = 655.42(7), c = 808.34(8) pm, α = 82.361(8), β = 89.173(9), γ = 71.980(7)°, Z = 2) exhibits zigzag chains {[(B1)o^t_1/1O^e_2/2(B2)O^t_1/1O^e_2/2]²⁻} (≡ {[BO₂]⁻}) of corner‐linked [BO₃]³⁻ triangles with syndiotactic orientation of the terminal oxygen atoms which are running parallel to the [100] direction. The Pr³⁺ cations are surrounded by three Cl⁻ and seven O²⁻ anions with the shape of a tetracapped trigonal prism. The green, transparent crystals of Pr(BO₂)₃ (monoclinic, C2/c; a= 984.98(9), b = 809.57(8), c = 641.02(6) pm, β = 126.783(9)°, Z = 4) appear either lath‐shaped or rather spherical. In the crystal structure the B³⁺ cations reside both in trigonal planar as well as in tetrahedral coordination of oxygen atoms. Both types of borate polyhedra ([BO₃]³⁻ and [BO₄]⁵⁻) are linked via corners to form chains of the composition {[(B2)‐O^t_1/1O^e_2/2(B1)O^e_4/2(B2)O^t_1/1O^e_2/2]³⁻} (≡ {[BO₂]⁻}) which run parallel [101]. The coordination sphere of the Pr³⁺ cations consists of ten oxide anions which build up a bicapped square antiprism.     

Synthesis,Structure, and Decomposition of (NH4)2[Mo6Cl14] · H2O

(NH₄)₂[Mo₆Cl₁₄] · H₂O ( 1 ) was prepared from reactions of MoCl₂ in ethanol with aqueous NH₄Cl solution. It crystallizes in the monoclinic space group I2/a (no. 15), Z = 4 with a = 912.3(1), b = 1491.2(2), c = 1724.8(2) pm, β = 92.25(1)°; R1 = 0.023 (based on F values) and wR2 = 0.059 (based on F² values), for all measured X‐ray reflections. The structure of the cluster anion can be given as [(Mo₆Cl)Cl]^2– (i = inner, a = outer ligands). Thermal stability studies show that 1 loses crystal water followed by the loss of NH₄Cl above 350 °C to yield MoCl₂. The water‐free compound (NH₄)₂[Mo₆Cl₁₄] ( 2 ) was synthesized by solid state reaction of MoCl₂ and NH₄Cl in a sealed quartz ampoule at 270 °C. No single‐crystals could be obtained. Decompositions of 1 and 2 under nitrogen and argon exhibited the loss of NH₄Cl at about 350 °C. Decomposition under NH₃ resulted in the formation of MoN and Mo₂N at 540 °C and 720 °C, respectively.