Structure and aggregation behavior of cobalt-di(2-ethylhexy1)-phosphoric acid complexes in solvent extraction systems

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Convex interpolating splines of arbitrary degree. III

For given data (x _i, f_i) _i=0 ⁿ (x ₀<x ₁<...<x _n) we consider the possibility of finding a spline functions of arbitrary degreek (k3) with preassigned smoothnessl, where 1l[(k-1)/2]. The splines should be such thats(x _i)=f _i (i=0, 1,...,n) ands is convex or nondecreasing and convex on [x ₀,x _n]. An explicit formula for this function as well as the conditions that guarantee the required properties are established. An algorithm for the determination of the splines and the error bounds is also included.     

Boden

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Structural, MALDI-TOF-MS, magnetic and spectroscopic studies of new dinuclear copper(II), cobalt(II) and zinc(II) complexes containing a biomimicking μ-OH bridge

The Py(2)N(4)S(2) octadentate coordinating ligand afforded dinuclear cobalt, copper and zinc complexes and the corresponding mixed metal compounds. The overall geometry and bonding modes have been deduced on the basis of elemental analysis data, MALDI-TOF-MS, IR, UV-vis and EPR spectroscopies, single-crystal X-Ray diffraction, conductivity and magnetic susceptibility measurements. In the copper and zinc complexes, a μ-hydroxo bridge links the two metal ions. In both cases, the coordination geometry is distorted octahedral. Magnetic and EPR data reveal weakly antiferromagnetic high spin Co(II) ions, compatible with a dinuclear structure. The magnetic characterization of the dinuclear Cu(II) compound indicates a ferromagnetically coupled dimer with weak antiferromagnetic intermolecular interactions. The intra-dimer ferromagnetic behaviour was unexpected for a Cu(II) dimer with such μ-hydroxo bridging topology. We discuss the influence on the magnetic properties of non-covalent interactions between the bridging moiety and the lattice free water molecules.     

Molecular modeling study of the aggregation behavior of nickel(II), cobalt(II), lead(II) and zinc(II) bis(2-ethylhexyl) phosphate complexes

The physiochemical nature of the metal-extractant species in organic solvent has been a matter of debate over liquid-liquid extraction of transition metals by bis(2-ethylhexyl) phosphate. The aggregation behavior of nickel(II), cobalt(II), lead(II), and zinc(II) bis(2-ethylhexyl) phosphate have been investigated using molecular modeling. The recently confirmed "open" water channels rodlike reversed micelles which is in contact with the nonaqueous solvent rather than in an inner core (or "closed" water channel) of the nickel-extractant species by Ibrahim and Neuman appears to be a unique structure for such species. Lead-, cobalt- and zinc-extractant species behave in a different manner. The cobalt-extractant species form rodlike reversed micelles, but does not show the formation of any open water channel. The zinc- and lead-extractant species form ellipsoidal (or deformed spherical) reversed micelles with fewer water molecules located at the core of the micelles which is in accord with the conventional view of reversed micelles. The structural variations of the reversed micelles for the metal extracted species are in accord with the known extraction behavior of such metals when using HDEHP.     

Crystal structure of 5α-bromo-8β,9α-dimethyl-hydrindane-1,4-dione

The molecular structure of 5-bromo-8,9-dimethylhydrindane-1,4-dione (C₁₁H₁₅BrO₂) has been confirmed using three-dimensional X-ray data collected by means of a Picker FACS-1 four-circle diffractometer. The compound crystallized in the space groupC2/c with unit cell constantsa = 26.56(5),b = 6.68(1),c = 12.32(2) Å and = 90.6(1) °; the density was 1.55 g cm^–3 andZ = 8. Least-squares refinement of the positional and anistropic thermal parameters gave a finalR ₁ value of 0.083 for 793 significant reflections.     

有机硅活性中间体的研究 II. 一些含环丙基的有机硅化合物的合成及其结构

用锂有机物的方法合成了四种含有环丙基有机硅化合物,对上述每种化合物中可能存在着的立体异构进行了分离和和构型测定。