Bis(4‐picoline‐κN)gold(I) dibromidoaurate(I) and bis(4‐picoline‐κN)gold(I) dichloridoaurate(I): space‐group ambiguity?

Bis(4‐picoline‐κN)gold(I) dibromidoaurate(I), [Au(C₆H₇N)₂][AuBr₂], (I), crystallizes in the monoclinic space group P2₁/n, with two half cations and one general anion in the asymmetric unit. The cations, located on centres of inversion, assemble to form chains parallel to the a axis, but there are no significant contacts between the cations. Cohesion is provided by flanking anions, which are connected to the cations by short Au...Au contacts and C—H...Br hydrogen bonds, and to each other by Br...Br contacts. The corresponding chloride derivative, [Au(C₆H₇N)₂][AuCl₂], (II), is isotypic. A previous structure determination of (II), reported in the space group P with very similar axis lengths to those of (I) [Lin et al. (2008). Inorg. Chem. 47 , 2543–2551], might be identical to the structure presented here, except that its γ angle of 88.79 (7)° seems to rule out a monoclinic cell. No phase transformation of (II) could be detected on the basis of data sets recorded at 100, 200 and 295 K.     

(±)-Mesembrine的全合成

以3-乙氧基-2-环己烯酮羰基邻位芳基化反应与Tsuji-Trost反应的串联反应作为关键步骤来构筑季碳中心, 完成了番杏科生物碱Mesembrine的全合成. 从商品化原料出发经6步反应以17.8%的总收率合成得到(±)-Mesembrine.     

Synthesis of (±)-cis-Calamenene;

Hydroboration of 4 furnishes a mixture of primary alcohols 5 and 6. The stereochemistry of the crystalline half ester 7 has been established by X-ray studies. While the oxidation of 5 with Jones reagent furnishes the aldehyde 9 in low yield due to the formation of the by product 3, oxidation with Moffatt reagent furnishes the aldehyde 9 in satisfactory yields. cis-Calamenene 1 has been prepared from 9.     

Crystal structures of chiral (R/S) (C<Subscript>8</Subscript>H<Subscript>11</Subscript>N)<Subscript>2</Subscript> · Zn(OAc)<Subscript>2</Subscript>

Two opposite configuration (R/S) of chiral complexes (C₈H₁₁N)₂ · Zn(OAc)₂ (Ia and Ib—L-(−)-) and D-(+)-isomer) were synthesized by a simple one-pot method. The crystal structures of Ia and ib determined by X-ray crystallography.     

Crystal structure and properties of (1,5-cyclooctadiene) (η<Superscript>5</Superscript>-pentamethylcyclopentadienyl) iridium(I) [Ir(cod)Cp*]

Volatile iridium(I) complexes [Ir(cod)Cp^x] (Cp^x = pentamethylcyclopentadienyl Cp*, ethylcyclopentadienyl Cp^Et, cod = 1,5-cyclooctadiene) are synthesized and characterized by IR and NMR spectroscopy. The [Ir(cod)Cp*] complex is a solid and the [Ir(cod)Cp^Et] complex is a liquid (SATP). The XRD method is used to determine the structure of the [Ir(cod)Cp*] complex: chemical formula C₁₈H₂₇Ir, space group P2₁/c, a = 8,4418(2) Å, b = 9,4764(3) Å, c = 19.2682(5) Å, β = 96.128(1) °, V = 1532.61(7) ų, Z = 4, d _calc = 1.888 g/cm³, μ = 8.697 mm^–1. The cyclopentadienyl ligand is η⁵-type coordinated; 1,5-cyclooctadiene have a cis-cis conformation and is η⁴-type coordinated. The thermal properties of the complexes are studied by thermogravimetry.     

Fabrication of multilayer ceramic structure for fuel cell based on La(Sr)Ga(Mg)O<Subscript>3</Subscript>–La(Sr)Fe(Ga)O<Subscript>3</Subscript> cathode

Fabrication by co-sintering method of a multilayer pore-free electrode–electrolyte structure promising for use in solid-oxide fuel cell and its characteristics have been studied. A material with high ionic conductivity of La_0.88Sr_0.12Ga_0.82Mg_0.18O_3–δ (LSGM) served as electrolyte. The composite electrode was formed from a 1: 2 mixture of LSGM and LSFG (La_0.7Sr_0.3Fe_0.95Ga_0.05O_3–δ). The maximum temperature of the materials co-sintering ability is 1250°C. It was shown by the impedance spectroscopy that the polarization resistance of the LSGM–LSFG electrode is 0.14 Ω cm² at 800°C.     

A review on green Lewis acids: zirconium(IV) oxydichloride octahydrate (ZrOCl<Subscript>2</Subscript>·8H<Subscript>2</Subscript>O) and zirconium(IV) tetrachloride (ZrCl<Subscript>4</Subscript>) in organic chemistry

Lewis acids are important and interesting catalysts in most organic transformations. Among different Lewis acids, Zr(IV) species such as ZrCl₄ and ZrOCl₂·8H₂O are allocated special attention because of their low toxicity, availability and handling, moisture stability, and low cost in comparison to some of their corresponding compounds. During recent decades, Lewis acids have been used to promote different types of organic reactions because they naturally possess mild acidity properties and, as such, can catalyze reactions selectively. This means that in the presence of various functional groups, they can operate on a specific group to produce the objective product. In this review we have focused on the reactions which have been progressed in the presence of ZrCl₄ and ZrOCl₂·8H₂O. The study has been ordered based on the number of the reaction components and their solvent media.     

<Emphasis Type="Italic">catena</Emphasis>-(μ<Subscript>3</Subscript>-Bromo)di(μ<Subscript>2</Subscript>-bromo)bromo(18-crown-6)dilead(II): Synthesis and crystal structure

A new polymeric complex, catena-(μ₃-bromo)di(μ₂-bromo)bromo(18-crown-6)dilead(II), [Pb₂Br(μ₂-Br)₂(μ₃-Br)(18-crown-6)] _n (I), is synthesized, and its crystal structure is studied using X-ray diffraction analysis (space group P \(\bar 1\), a = 7.970, b = 16.048, c = 19.153 Å, α = 72.75°, β = 88.57°, γ = 87.92°, Z = 4, direct method, full-matrix least-squares method in the anisotropic approximation, R = 0.076 for 6093 independent reflections, CAD4 automated diffractometer, λMoK_α radiation). The crystal structure of complex I contains infinite chains of the PbBr₆ octahedra along the x axis with the bridging Br^? anions as common edges. The [PbBr(18-crown-6)]⁺ host-guest complex fragments are attached through weak Pb-Br bonds to these chains on the side. In two independent terminal fragments, the coordination polyhedra of the Pb²⁺ cations are distorted hexagonal bipyramids with bases of six O atoms of the crown ligand and two Br^? anions in the axial vertices. Two Pb²⁺ cations from the [PbBr₃] _n ^? infinite polymer chain have a distorted octahedral coordination.     

Erbium(III) and lutecium(III) complexes [Ln(H<Subscript>2</Subscript>O)<Subscript>8</Subscript>][Cr(NCS)<Subscript>6</Subscript>] · 5H<Subscript>2</Subscript>O: Synthesis and crystal structure

[Ln(H₂O)₈][Cr(NCS)₆] · 5H₂O aqua complexes, where Ln = Er (1), Lu (2), have been found in an aqueous solution instead of binary complex salts with an organic ligand in their cation, when crystal products of the reaction between Ln(NO₃)₃ · 6H₂O (Ln = Er, Lu), K₃[Cr(NCS)₆] · 4H₂O, and 8-oxyquinoline (C₉H₇NO) were studied by X-ray diffraction. Crystals of complexes 1 and 2 are isostructural and crystallize in triclinic system, space group P\(\bar 1\), Z = 2. For complex 1: a = 9.0677(4) Å, b = 9.3115(4) Å, c = 16.9595 Å, α = 81.526(2)°, β = 86.153(2)°, γ = 83.879(2)°, V = 1406.33(10) ų, ρ_calc = 1.894 g/cm³; for complex 2: a = 9.0438(3) Å, b = 9.2880(3) Å, c = 16.9181(3) Å, α = 81.7250(10)°, β = 86.1600(10)°, γ = 83.8850(10)°, V = 1396.38(7) ų, ρ_calc = 1.926 g/cm³.     

(Vapour + liquid) equilibria for the binary mixtures (cis-pinane + α-pinene) and (cis-pinane + 1-butanol)

The isothermal and isobaric (vapour + liquid) equilibria for (cis-pinane + α-pinene) and (cis-pinane + 1-butanol) measured with an inclined ebulliometer are presented. The experimental results are analysed using the UNIQUAC equation with the temperature-dependence binary parameters with satisfactory results. Experimental vapour pressures of cis-pinane are also included.     

(Indenyl)iridacarborane (η<Superscript>5</Superscript>-indenyl)Ir(η-7,8-C<Subscript>2</Subscript>B<Subscript>9</Subscript>H<Subscript>11</Subscript>): synthesis,structure, and bonding

A reaction of iodide [(η⁵-indenyl)IrI₂]_n (1) with thallium dicarbollide Tl[Tl(η-7,8-C₂B₉H₁₁)] leads to (indenyl)iridacarborane (η⁵-indenyl)Ir(η-7,8-C₂B₉H₁₁) (2) in 32% yield. The X-ray diffraction study showed that in the structure of 2, the five-membered rings C₅ and C₂B₃ have a cisoid conformation, in which the bridgehead carbon atoms of the indenyl ligand are arranged opposite to the carborane cage carbon atoms. The DFT calculations showed that the Ir—indenyl bond in compound 2 is weaker than the Ir—Cp bond in the complex (η-7,8-C₂B₉H₁₁)IrCp.     

Crystal structure of <Emphasis Type="Italic">N</Emphasis>-(3-hydroxypropyl)-β-alanine and Bis(<Emphasis Type="Italic">N</Emphasis>-(3-hydroxypropyl)-β-alaninato)dicopper(II) [Cu<Subscript>2</Subscript> (Pro-ala)<Subscript>2</Subscript>]

N-(3-Hydroxypropyl)-β-alanine was synthesized by the reacti on of 3-aminopropanol with acrylic acid. From this ligand and basic copper carbonate, bis(N-(3-hydroxypropyl)-β-alaninato)dicopper(II) [Cu₂ (C₆H₁₁NO₃)₂] was obtained. The structures of the chelating agent and the copper complex were studied by X-ray diffraction. The Cu(II) coordination polyhedron is a distorted square pyramid. Each ligand forms six-membered β-alaninate and propanolamine chelate rings. The propoxy group functions as a bridge. In the crystal structure, the molecules form intermolecular coordination bonds C=O→Cu, which are perpendicular to the layers. The EPR signal typical of dimeric copper complexes is not observed due to low occupancy of the excited paramagnetic triplet state. The weak paramagnetic signal from monomeric copper complex allowed recording of the ¹H NMR spectrum of [Cu₂ (Pro-ala) ₂] with characteristic line broadening and contact shift. It follows from the obtained data that on dissolution, the complex dissociates by 40% to give monomeric copper complexes.     

Oxidation of Fe(III) to Fe(VI) by the Fe(CN)<Stack><Subscript>6</Subscript><Superscript>3−</Superscript></Stack> ion in strong solution of alkalis

Ferricyanide ions oxidize Fe(III) up to Fe(VI) in 7–11 M KOH solutions and 10–16 M NaOH solutions. The completeness of the oxidation increases with increasing alkali and ferricyanide concentrations. The presence of KNO₂, KAc, and K₂C₂O₄ in 7 M KOH solution increases the Fe(VI) yield. Potassium fluoride in the concentration of 0.02 M does not hinder Fe(VI) formation, but in the concentration of 0.1 M completely suppresses Fe(III) oxidation. The attempt to oxidize Fe(VI) up to Fe(VIII) by the disproportionation of Fe(VI) or by the action of Fe(CN)₆³⁻ and ozone was unsuccessful due to a high oxidation potential of the Fe(VIII)/(VI) couple.     

(±)-脱落酸的合成

以β-紫罗兰酮为起始原料,经环氧化、开环、烯丙位氧化、Wittig反应、碱性水解5步反应,以39％的总收率合成了植物激素3-甲基-5-(1-羟基-4-氧代-2,6,6-三甲基-2-环己烯基)-2,4-戊二烯酸(脱落酸),用IR、¹H NMR、MS及元素分析等测试技术表征了产物的结构。     

Synthesis and spectral studies on NiS<Subscript>4</Subscript>, NiS<Subscript>2</Subscript>PN,NiS<Subscript>2</Subscript>P<Subscript>2</Subscript> chromophores: Single-crystal X-ray structure of [Ni(dbpdtc)<Subscript>2</Subscript>] (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate)

Three complexes of a dithiocarbamate ligand (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate), namely [Ni(dbpdtc)₂] (1), [Ni(dbpdtc)(NCS)(PPh₃)] (2) and [Ni(dbpdtc)(PPh₃)₂]ClO₄ (3) have been prepared. The complexes were characterized by IR, electronic spectroscopy and cyclic voltammetry. A single-crystal X-ray structural analysis was carried out for complex 1 and showed that the nickel is in a distorted square planar environment with a NiS₄ chromophore. For the two mixed ligand complexes, the thioureide ν _C–N values were shifted to higher wavenumbers compared to [Ni(dbpdtc)₂], suggesting increased strength of the thioureide bond due to the presence of the π-accepting phosphine. Electronic spectral studies suggest square planar geometries for the complexes. Cyclic voltammetry showed easier reduction of nickel(II) to nickel(I) in the mixed ligand complexes compared to [Ni(dbpdtc)₂].     

Poly(?-caprolactone)-based ‘green’ plasticizers for poly(vinyl choride)

A series of proposed plasticizers for poly(vinyl chloride) (PVC), based on poly(?-caprolactone) (PCL) with octanoate and benzoate-terminal groups, were synthesized with various microstructures and molecular weights (MW) and tested for biodegradability as well as for mechanical performance, and leaching resistance in blends with PVC. The plasticization efficiency of each was characterized by measuring the glass transition temperature (T_g) and tensile properties of PCL/PVC blends. The PCL-octanoate plasticizers demonstrated plasticization efficiency similar to di(ethylhexyl) phthalate (DEHP) with the same plasticizer loading. PCL-benzoate/PVC blends had much higher T_gs (∼20 °C higher) compared to PCL-octanoate/PVC and DEHP/PVC blends. Yield stresses were about two times higher for PCL-benzoate/PVC blends compared to PCL-octanoate/PVC and DEHP/PVC blends, reflecting the stiffer nature of such blends. Biodegradation was rapid for all PCL-octanoates, with the exception of linear PCL-octanoates with arm molecular weights >10³ g mol⁻¹. Biodegradation rates of PCLs by Rhodococcus rhodocrous were not affected by microstructure for the range of PCL topologies studied (linear versus three or four arms) but were slower for PCLs made from commercial PCL-diols that had a central ether linkage due to the initiator used to make these compounds. Leaching resistance was higher as PCL molecular weight increased and, for pairs of comparable sized species, significantly less PCL-benzoate leached out compared to the PCL-octanoate. For the range of PCL topologies studied, the number of arms did not significantly affect leaching resistance. In summary, both the end group and the molecular weight influenced the leaching resistance of the PCL. PCL-octanoates were comparable plasticizers to DEHP in terms of the mechanical properties examined, and were rapidly degraded by a common soil microorganism.