Circular dichroism of optically active planar chiral cyclopalladium ferrocene derivatives. Investigation of the dimer-monomer equilibrium

The concentration dependence of the circular dichroism spectra of optically active dinuclear 2-dimethylaminomethylferrocenylpalladium chloride was studied in two solvents. The observed changes in the position and intensity of the Cotton effects were interpreted as a consequence of the dimer-monomer equilibrium. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1411–1413, July, 2007.     

EuCN2 — The First,but Not Quite Unexpected Ternary Rare Earth Metal Cyanamide

Red‐orange, transparent single crystals of EuCN₂ (Pnma (62), a = 1232.41(9), b = 395.26(3) and c = 539.43(4) pm, Z = 4) are obtained by the reaction of EuN, C and NaN₃ in arc‐welded Ta ampoules at 1300 K. The first ternary rare earth metal cyanamide is isotypic to α‐SrCN₂ and shows the characteristic frequencies for the CN₂^2— unit in the optical spectra (ν_s = 1244; ν_as = 1969 and 2087; δ = 655 / 666 cm^—1).     

Invited review “sol-gel” preparation of high temperature superconducting oxides

This review article focuses on the sol-gel preparation of high temperature superconducting oxides wherein different classes of gel technologies were utilized. These involve: 1) the sol-gel route based upon hydrolysis-condensation of metal-alkoxides, 2) the gelation route based upon concentration of aqueous solutions involving metal-chelates, often called as chelate gel or amorphous chelate route, and 3) the organic polymeric gel route. This paper reviews the current status of these sol-gel processes, and illustrates the underlying chemistry involved in each sol-gel technology. It is demonstrated that the chemical homogeneity of the gel is often disturbed by the differences in the chemistries of the cations. Prior to gelation the starting precursor solution containing various forms of metal-complexes must be chemically modified to overcome this problem. Illustration of a variety of strategies for success in obtaining a homogeneous multicomponent gel with no precipitation is focal point of this review article.strictly speaking, sol-gel must include processing, in which a sol (often defined as a suspension of small but discrete particles remaining dispersed in a liquid phase) undergoes a transition to a gel characterized by an infinite three-dimensional network structure spreading uniformly throughout the liquid medium. Thus a gel has to be distinguished either from a viscous liquid of one continuous phase or from a gelatinous precipitate in which a liquid phase is not involved in the solid network. It is generally accepted that a true gel can be prepared in two major chemical ways: (1) a molecular route based upon hydrolysis and polycondensation of metal alkoxides (alkoxide gels) and (2) a network formation route based upon destabilization of dispersed colloidal particles in a liquid medium (particulate gels). According to the rigorous definition of gel, some solution processes, started from metal-organics (other than metal alkoxide), would not be classified into a true sol-gel process. In this paper, however, the term sol-gel is broadly used to describe the preparation of inorganic materials by a variety of solution routes. A chemical process which can produce a solid matter or a highly viscous liquid matter with no precipitation is treated as the so-called sol-gel process, even when it is likely that the system contains no infinite rigid network.     

Kinetics of europium(III) transport through a liquid membrane containing HEH(EHP) in kerosene

Coupled transport of Eu(III) ions through a bulk liquid membrane containing mono(2-ethylhexyl)2-ethylhexyl phosphonate [HEH(EHP)] in kerosene has been examined. The influences of the carrier concentration, the HCl concentration in the stripping solution, the pH in the feed solution and the temperature were investigated. The transport of the Eu(III) ions is coupled by counter-transport of protons. The kinetics of the Eu(III) transport could be analyzed in the formalism of two consecutive irreversible first order reactions. The pseudo-first order apparent rate constants of the interfacial transport of the Eu(III) species are determined, varying temperature. The activation energy values are 14.0±1.0 and 54.0±3.4 kJ mol⁻¹ for extraction and stripping, respectively.     

Schiff碱铜(Ⅱ)络合物和甘油-聚乙烯微胶囊改性超高分子量聚乙烯的磨损机理研究

将所合成的乙二胺缩水杨醛Schiff碱铜（Ⅱ）络合物和甘油-聚乙烯微胶囊与超高分子量聚乙烯（UHMWPE）共混制备出改性UHMWPE材料,利用销-盘式摩擦磨损试验机评价Schiff碱铜（Ⅱ）络合物和甘油．聚乙烯微胶囊改性UHMWPE／GCr15钢配副在高速干摩擦条件下的摩擦磨损性能,利用扫描电子显微镜观察其磨损表面形貌,采用电子能谱仪分析磨损表面的主要元素组成并探讨其磨损机理．结果表明,由于其独特的自身选择性转移效应使得耐磨性提高,在高速干摩擦条件下没有严重的粘着磨损．     

铕(Ⅲ)-苯甲酸衍生物配位化合物中Eu(Ⅲ)离子格位

以 2 ,3 二甲氧基苯甲酸 (2 ,3 HDMOBA)和 4 甲基苯甲酸 (p HMBA)为配体 ,合成了新的稀土配合物Eu(2 ,3 DMOBA) 3 和Eu(p MBA) 3 。在 77K下测定了高分辨激发光谱和时间分辨谱。配合物Eu(2 ,3 DMOBA) 3中Eu(Ⅲ )离子格位只有一种 ,配合物Eu(p MBA) 3 中确有化学环境类似的多种类型的Eu(Ⅲ )离子。     

Metal chelates of benzimidazolylazo derivatives

Summary The complexation of 2-(4-benzimidazolylazo)-R-acid and 5-(4-benzimidazolylazo)-8-hydroxy-quinoline with Mn(II), Co(II), Ni(II), and Cu(II) have been studied potentiometrically using the Calvin-Bjerrum titration technique as employed by Irving and Rossotti. Protonation constants of the ligands and stability constants of the metal complexes have been determined at constant temperature (25|dgC) and ionic strength (0.1 µ NaCl). The order of stability constants (log₁), Mn(II) < Co(II) < Ni(II) < Cu(II) is in conformity with the Irving-Williams order. The structures of the solid complexes have been assigned on the basis of elemental analysis and IR spectroscopy. Also conductimetric titrations have been made to characterize the composition of the complexes.

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Metallchelate von Benzimidazolylazo-Derivaten

Zusammenfassung Es wurde die Komplexierung von 2-(4-Benzimidazolylazo)-2-hydroxynaphthalin-3,6-disulfonsäure und 5-(4-Benzimidazolylazo)-8-hydroxychinolin mit Mn(II), Co(II), Ni(II) und Cu(II) potentiometrisch mittels der Calvin-Bjerrum-Titrationsmethode in der Modifikation von Irving-Rossotti untersucht. Die Protonierungskonstanten der Liganden und die Stabilitätskonstanten der Metallkomplexe wurden für eine Temperatur von 25|dgC und eine Ionenstärke von 0.1 µ (NaCl) bestimmt. Die Reihung nach Stabilitätskonstanten (log ₁), Mn(II) < Co(II) < Ni(II) < Cu(II), ist in Übereinstimmung mit der Irving-Williams-Ordnung. Die Strukturen wurden mittels Elementar-analyse und IR-Spektroskopie charakterisiert. Zur Ermittlung der Zusammensetzung der gebildeten Komplexe wurden auch Leitfähigkeitsmessungen durchgeführt.

     

萃取-原子吸收光谱法测定高纯氧化铕、氧化钐中的锌

在ＰＨ３的弱酸性介质中,用吡咯烷二硫代氨基甲酸铵－甲基异丁基酮萃取分离稀土氧化物以消除基体干扰;用火焰原子吸收光谱法测定了氧化铕、氧化钐中的痕量锌,相对标准偏差分别为５．８％,３．６％;试样加标回收率分别为９７％－９８％,９５％－１０２％。     

Crystal structure and luminescence property of novel three-dimensional network of {Eu2(p-BDC)3(Phen)2(H2O)2}n

The single crystal of a supramolecule, {Eu₂(p-BDC)₃(Phen)₂(H₂O)₂}_n (p-BDC=1,4-benzenedicarboxylate), with characteristic luminescence of Eu³⁺ was obtained by means of soft chemistry. The crystal structure determination reveals that each Eu³⁺ ion is coordinated by five oxygen atoms of p-BDC anions, one oxygen atom from water molecule, and two nitrogen atoms of Phen, respectively, resulting in an eight-coordinated Eu³⁺ center and a distorted square antiprism coordination polyhedron. Four bridges, two carboxylates of μ₄-p-BDC and two of μ₃-p-BDC, connect two Eu atoms into a binuclear unit. Moreover, the μ₃-p-BDC integrates the binuclear building blocks at the direction of b axis and the μ₄-p-BDC polymerizes the structure roughly along the direction of the sum vector of axis b and c, respectively, forming two-dimensional layers. Hydrogen bonds between layers make the structure a three-dimensional network. The luminescence spectra measured under 77 K demonstrate the antenna effect of Phen and the ⁵D₁→⁵D₀ energy transfer path within Eu³⁺ ion. Both luminescence spectra and crystal structure lead to the conclusion that the local symmetry around the Eu³⁺ ion is C₁ and that more than one Eu³⁺ ion sites having slight environmental difference are present.     

First Homoleptic Rare Earth Carbazolates: Synthesis,Crystal Structures,Spectroscopic and Thermal Investigations of Divalent 1[Ln(NC12H8)2] with Ln = Europium and Ytterbium

The compounds [Ln(NC₁₂H₈)₂], Ln = Eu and Yb, were obtained in solvent free reactions of the rare earth elements europium and ytterbium with the amine carbazole. Single crystals of both compounds were grown from the melt syntheses, no recrystallization from solvents was necessary. The new compounds are the first examples of homoleptic carbazolates of the rare earth elements furthermore exhibiting divalent lanthanides. In absence of any solvent, carbazole as the sole coordination partner shows η⁶‐π‐coordination in addition to the μ₁‐ and μ₂‐coordination of the nitrogen atoms. This results in a one‐dimensional chain structure of dimers with a formal C.N. of 6 for the rare earth elements and thus being low for divalent lanthanides. The products were investigated by X‐ray single crystal and powder diffraction, Mid IR, Far IR and Raman spectroscopy, and with DTA/TG regarding their thermal behaviour. Both compounds [Ln(NC₁₂H₈)₂], Ln = Eu (1) and Yb (2) , crystallize isotypic in the triclinic space group P1.