Etude d'un modele de reaction electrochimique d'insertion—II. commande lineaire en tension—etude formelle

A mathematical model of cation intercalation in a host lattice is studied. Theoretical current-potential curves in linear sweep voltammetry are calculated for plane, cylindrical or spherical electrodes. The variation of these curves with non-dimensional parameters are studied. A kinetic analysis of model behaviors is done by the kinetic zone diagram method. The possibility of measuring real systems parameters is also discussed.     

Coordination of cobalt(III), nickel(II), copper(II), palladium(II) and platinum(II) with N-ethyl-N′-(4′-methylthiazol-2′-yl)thiourea (HL)

Coordination complexes of formula [ML₂], [CoL₃], [Pd(HL)Cl₂], [CuLCl(H₂O)] and [CuL₂(H₂O)₂] {L=anion of N-ethyl-N^′-(4^′-methylthiazol-2′-yl)thiourea; M=Pt^II, Pd^II or Ni^II} were prepared and characterized by elemental analyses, magnetic susceptibilities, and by IR, NMR, electronic and mass spectral measurements.     

4′-(Oxodiphenylphosphino)-2,2′:6′,2′′-terpyridine – crystal structure and complexes of cobalt(II) and cobalt(III)

The complex [Co(2)₂]²⁺ (2 = 4^′-(oxodiphenylphosphino)-2,2^′:6^′,2^′′-terpyridine) has been prepared either by the direct reaction of 2 with Co(II) or by careful oxidation of [Co(1)₂]²⁺(1 = 4^′-(diphenylphosphino)-2,2^′:6^′,2^′′-terpyridine). Further oxidation with H₂O₂ leads to [Co(2)₂]³⁺. The ¹H NMR spectra of the paramagnetic and diamagnetic [Co(2)₂]²⁺ and [Co(2)₂]³⁺ are reported. The crystal structure of ligand 1 has been determined; in the solid-state, 1 exhibits extensive intermolecular π–π stacking.     

Ferromagnetic interactions in a bis(μ-end-on azido)cobalt(II) linear trimer

A linear trinuclear Co(II) compound, [Co₃(μ_1,1-N₃)₄(N₃)₂(H₂O)₂(bpbp)₂] · 2H₂O (1, bpbp = 3,3′-bis-Dimethylamino-1,1′-pyridine-2,6-diyl-bispropenone), is reported. The central Co(II) ion is bridged to Co(II) ions on both sides by four end-on azide (${\mathrm{\mu }}_{1\text{,}1}\text{-}{\text{N}}_3^{-}$) ligands resulting in a centrosymmetric trimer with adjacent Co?Co distance of 3.233 Å. Each Co(II) ion possesses distorted octahedral geometry, the central one is coordinated by two aqua ligands and four ${\mathrm{\mu }}_{1\text{,}1}\text{-}{\text{N}}_3^{-}$ nitrogen atoms and each terminal Co(II) is coordinated by two ${\mathrm{\mu }}_{1\text{,}1}\text{-}{\text{N}}_3^{-}$ nitrogen atoms, one terminal ${\text{N}}_3^{-}$ nitrogen atom and capped by terminal tridentate bpbp ligand. Variable temperature magnetic studies indicate ferromagnetic coupling between adjacent Co(II) ions within the trimer.     

An unprecedented mixed valence cobalt(III)/cobalt(II) ion-pair complex ([CoCO3(bipy)2]2[Co(DCA)2]⋅16H2O) with two novel water tapes

An unprecedented mixed valence cobalt(III)/cobalt(II) ion-pair complex, [CoCO₃(bipy)₂]₂[Co(DCA)₂]⋅16H₂O (1) [bipy = 2,2′-bipyridine, DCA = demethylcantharidate, exo-1,4-epoxy-cyclohexyl-2,3-dicarboxylate group, (C₈H₈O₅)^2 −], has been synthesized and characterized by elemental analysis, IR, UV–vis, Thermogravimetric analysis (TGA) and single crystal X-ray diffraction. The crystal structure of 1 consists of three independent molecular moieties: [CoCO₃(bipy)₂]⁺, [Co(DCA)₂]^2–, and water molecules of crystallization. Interestingly, two novel water tapes, one comprises of alternate cyclic water tetramer and octamer, the other is constructed by alternate cyclic water hexamer and carboxylate–water hybrid octamer [(H₂O)₂(COO)₂]^2 −, have been detected for the first time in the host framework of 1. The two novel water tapes are linked together by the DCA and carbonate ligands via hydrogen bonds into a 2D water layer, and then the water layers assemble complex ions ([CoCO₃(bipy)₂]⁺ and [Co(DCA)₂]^2 −) through hydrogen bonds, π–π interactions and electrostatic interactions to form the overall 3D metal–organic framework structure.     

人工神经网络光度法同时测定水中Fe(II)、Fe(III)

应用径向基函数人工神经网络(RBF)和误差反向传播神经网络(BP),采用磺基水杨酸-邻菲罗啉双显色剂光度法同时分析了水中Fe(II)和Fe(III)。实验证明,RBF算法在所需神经元个数、训练时间、预测准确度等方面均明显优于BP网络算法。该技术和光度法结合有望成为多组分分析的有效选择方法之一。     

Low temperature preparation of fluoroalkanes from a mixture of carbon tetrachloride,dichloromethane and anhydrous hydrogen fluoride using a fluorinated γ-alumina supported iron(II,III)/cobalt(II,III) oxide catalyst

1,1,1,2-tetrafluoroethane has been prepared at 473 K under static conditions, from a feedstock of carbon tetrachloride, dichloromethane and anhydrous hydrogen fluoride using a-alumina supported fluorinated Co(II, III)₈₅Fe(II, III)₁₅O_x catalyst. Conversion to hydrofluoroalkanes was ca. 58% efficiency as quantified by liquid phase¹⁹F NMR analysis.     

Selective Eu(III) Electro‐Reduction and Subsequent Separation of Eu(II) from Rare Earths(III) via HDEHP Impregnated Resin

Abstract

Eu(III) was selectively reduced to Eu(II) at three‐dimensional glassy carbon cathode in 0.01 mol · dm^?3 hydrochloric acid medium. Eu(III) reduction took place after all the dissolved oxygen was reduced and then proceeded steadily. Separation of Eu(II) from trivalent rare earths (La, Ce, Sm, Gd, Er, Yb) was carried out using a novel impregnated resin based on bis(2‐ethylhexy1)phosphoric acid. Eu(II) showed much lower affinity towards the resin than the trivalent rare earths and broke through the column readily. Eu of purity higher than 99.8% was yielded. The back‐oxidation of Eu(II) was observed during the sorption and Eu(III) was absorbed onto the resin. Adsorbed light and middle rare earths could be stripped from the loaded resin by 3M hydrochloric acid. Stripping of heavy rare earths (Er, Yb) was problematic.     

Stabilite cathodique des pinacols—comportement des β-di-Sulfopinacols en milieu non aqueux

The cathodic stability of β-di-sulfopinacols, in non aqueous medium was studied by means of cyclic voltammetry. The mechanism of degradation of β-di-sulfopinacols, occurring by acid—base reaction between acidic substrate and electrogenerated bases, is considered to proceed via formation of either benzile or the corresponding α,β-ethylenic sulfone, depending on the aromatic or the aliphatic nature of sulfonyl group. In both cases, the mechanism involves the formation of acetophenone, which becomes preponderant in a strongly basic medium.     

Trinuclear cobalt(II) sandwiched polyoxotungstobismuthate with antennal copper(II)-complex: A new method to combine hetero–transition–metallic ions

A new sandwich-type hybrid complex, Na₈{Cu(im)₄(H₂O)}[Cu(im)₄ {Na(H₂O)₂Co(im)}₃(BiW₉O₃₃)₂] · 11H₂O (1) (im = imidazole), has been synthesized and structurally characterized. The polyoxoanion in 1 contains trinuclear Co²⁺ ions in the central belt and an antennal Cu(II)–imidazole supported complex, which firstly represents a copper(II)-complex mono-supported tungstobismuthate system containing sandwiched trinuclear cobalt(II) ions. Neighboring polyanions further connect each other by disodium ions to yield a dimeric complex. The successful synthesis of 1 opens a new approach to the combination of different kinds of transition–metal ions by virtue of lacunary Keggin-type polyoxoanions, [BiW₉O₃₃]^9?, as effective linkages. The magnetic investigation for 1 indicate weak antiferromagnetic interactions for trinuclear Co(II) clusters located in the polyanions.     

Copolymerization of carbon monoxide and styrene with the Nd(III)–Cu(II) catalyst

In this article, the linear alternating copolymer of carbon monoxide and styrene was obtained using the Nd(III)–Cu(II) catalyst. It was found that the introducing order of the catalyst components can affect the catalytic activity, and the pre-prepared catalyst had higher catalytic activity than the in situ catalyst. The promoting effect of copper acetate on the catalytic activity was also investigated. The structure of the copolymer was characterized by means of IR, ¹H-NMR, ¹³C-NMR, WXRD, and EA methods. The thermal decomposition properties were checked by the way of TGA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 8–13, 2001     

Synthese electrochimique de l'acide glyoxylique a partir du glyoxal—II. influence des adatomes sur les courbes de voltammetrie cyclique du glyoxal,de l'acide glyoxylique et de l'acide oxalique sur platine

The influence of the addition of nine adatoms (Pd, Ru, Ag, Au, Tl, Pb, Bi, Sn, Cu) on the cyclic voltammetry oxidation curves of glyoxal, glyoxylic acid and oxalic acid is studied on platinum in aqueous N HClO₄ medium. A cathodic shift and an increase of the current peak are observed with Tl, Ag, Au for all the organic species. On the other hand the addition of Sn, Ru and Cu(I) lead to an anodic shift and generally a decrease of the intensity of the current peaks.     

Synthesis of pure (Co) polymers via supported cobalt (II)-catalyzed controlled/“living” radical polymerization

Cross-linked polyacrylic resin supported-cobalt (II) catalyst was successfully employed in controlled/“living” radical polymerization of various monomers including n-butyl acrylate (BA), ethyl methacrylate (EMA) and styrene (St). Well-defined polymers with predetermined molecular weight and relatively narrow molecular weight distribution were synthesized. After polymerization, the supported cobalt (II) catalyst was easily and effectively removed from the polymerization system by simple centrifugation and very pure polymer products were obtained (Co residue <0.1 ppm). Using the obtained polymers as macroinitiators, polymerization of methyl methacrylate (MMA) and fluorinated methacrylate ether 2-[(perfluorononenyl)oxyl] ethyl methacrylate (FNEMA) were performed, respectively. Well-defined and pure diblock copolymers PBA-b-PMMA, PS-b-PMMA and PS-b-PFNEMA were synthesized.     

Ni(II)–Mg(II)–Al(III) catalysts for hydrogen production from ethanol steam reforming: Influence of the activation treatments

The effect of the Ni(II)–Mg(II)–Al(III) layered double hydroxide (LDH) activation conditions over the surface and bulk composition and the catalytic performance in ethanol steam reforming (ESR) is studied. Ternary oxides were prepared by thermal decomposition of LDHs synthesized using the homogeneous precipitation method with urea. Catalyst precursor is submitted to two different activation treatments: calcinations at 400, 500, 600 and 700 °C with subsequent reduction at 720 °C, or direct reduction at 720 °C. The samples were characterized by sorptometry, H₂ chemisorption, ICP chemical analysis, thermogravimetric analysis, X-ray diffraction, X-ray photoelectronic spectroscopy and temperature programming reduction. The catalysts obtained by calcination at 600 °C and then reduction at 720 °C and those directly reduced at 720 °C showed the better performance in ESR. The precursor submitted to a proper thermal treatment develops, through a decoration-demixing process, a Ni(II)-poor spinel-type shell onto NiO domains.     

Oxidation of cobalt(II) to cobalt(III) in the presence of phosphorus and sulphur donors via –O–C bond cleavage: synthesis and structure of [CoIII(dppe)(EtOCS2)(COS2)] (dppe=1,2-bis(diphenyl phosphino)ethane)

An ethanolic solution of cobalt(II) reacts with dppe (1,2-bis(diphenyl phosphino)ethane) and etxant (ethyl xanthate) affording an intensely coloured Co^III complex, [Co^III(dppe)(etxant)(COS₂)], by eliminating [EtOC(S)(SEt)] via –O–C bond rupture. The structure of the cobalt(III) complex has been confirmed by X-ray crystallography, NMR and mass spectrometry.     

A novel cyano-bridged Sr(II)–Fe(III) polymer containing alternating octanuclear and tetranuclear cores

A novel cyano-bridged Sr(II)–Fe(III) polymeric complex ([Sr₃(phen)₆(H₂O)₆{Fe(CN)₆}₂]·phen·6.5H₂O)_n (1) has been synthesized and structurally characterized. The complex contains alternating octanuclear 24-membered and tetranuclear 12-membered metallocycles, which are repeated to form a polymeric chain. The Sr(II) centres are eight coordinated with distorted bicapped trigonal prismatic geometry while the Fe(III) centres have six coordinate octahedral geometry.     

叔胺萃取分离钴(II)、铁(II)

研究了不必预先氧化二价铁,直接用叔胺从氯化物溶液中萃取分离钴(II)、铁(II)的新方法. 考察了不同改性剂对叔胺萃取钴(II)、铁(II)的影响以及各种因素对钴(II)、铁(II)萃取、洗涤及反萃的影响. 提出了用叔胺萃取分离钴(II)、铁(II)的最佳工艺参数.     

Attenuation of Combined Nickel(II) Oxide and Manganese(II,III) Oxide Nanoparticles’ Adverse Effects with a Complex of Bioprotectors

Stable suspensions of NiO and Mn₃O₄ nanoparticles (NPs) with a mean (±s.d.) diameter of 16.7 ± 8.2 and 18.4 ± 5.4 nm, respectively, purposefully prepared by laser ablation of 99.99% pure nickel or manganese in de-ionized water, were repeatedly injected intraperitoneally (IP) to rats at a dose of 2.5 mg/kg 3 times a week up to 18 injections, either alone or in combination. A group of rats was injected with this combination with the background oral administration of a “bio-protective complex” (BPC) comprising pectin, vitamins A, C, E, glutamate, glycine, N-acetylcysteine, selenium, iodide and omega-3 PUFA, this composition having been chosen based on mechanistic considerations and previous experience. After the termination of injections, many functional and biochemical indices and histopathological features (with morphometric assessment) of the liver, spleen, kidneys and brain were evaluated for signs of toxicity. The Ni and Mn content of these organs was measured with the help of the atomic emission and electron paramagnetic resonance spectroscopies. We obtained blood leukocytes for performing the RAPD (Random Amplified Polymorphic DNA) test. Although both metallic NPs proved adversely bio-active in many respects considered in this study, Mn₃O₄-NPs were somewhat more noxious than NiO-NPs as concerns most of the non-specific toxicity manifestations and they induced more marked damage to neurons in the striatum and the hippocampus, which may be considered an experimental correlate of the manganese-induced Parkinsonism. The comparative solubility of the Mn₃O₄-NPs and NiO-NPs in a biological medium is discussed as one of the factors underlying the difference in their toxicokinetics and toxicities. The BPC has attenuated both the organ-systemic toxicity and the genotoxicity of Mn₃O₄-NPs in combination with NiO-NPs.