基于杂环有机锡化合物的水杨酸根离子选择电极研究

A novel heterocyclic haxacoordinated organotin(Ⅳ) complex, bis (o-vanillin)-semi-ethylenediamine dibenzyltin (VEDBT) was synthesized and used as anion ionophore for PVC membrane electrode; the novel electrode exhibits a linear response towards salicylate and an anti-Hofmeister selectivity pattern with high specificity for salicylate over many common anions, the selective pattern is: Sal^- > SCN^- > ClO₄^- > I^- > NO₂^- > NO₃^- > Cl^- ≈ Br^- > SO₄^2-. The behaviour of the electrode is influenced by the experimental conditions. The response mechanism was also investigated by UV spectroscopy. The electrode was applied to the determination of salicylate in pharmaceutical samples with satisfactory results.     

碱性介质中 (氢) 氧化铜修饰电极电催化氧化蔗糖

 A stable copper (hydr)oxide-modified electrode was prepared in 0.5 mol/L NaOH solution by cyclic voltammetry in the range of -250 to 1 000 mV. It can be used for electrochemical studies in the range of -250 to 1 000 mV without interfering peaks because there is no oxidation of copper. During an anodic potential sweep, the electro-oxidation of saccharose on Cu occurred by the formation of Cu^III and this reaction also occurred in the early stages of the reversed cycle until it is stopped by the negative potentials. A mechanism based on the electro-chemical generation of Cu^III active sites and their subsequent consumption by saccharose was proposed, and the rate law and kinetic parameters were obtained. The charge transfer resistance from theoretical and impedance studies was used to verify the mechanism. Under chronoamperometry regimes, the reaction followed Cottrellian behavior. The transfer of up to 21 electrons was observed in further investigations of the electro-oxidation of saccharose on a (hydr)oxide Cu rotating disk electrode.     

Mn(Ⅱ)和Ce(Ⅳ)离子对铬酸氧化乳酸的影响

The kinetics and mechanism of lactic acid oxidation in the presence of Mn(II)and Ce(IV)ions by chromic acid were studied spectrophotometrically.The oxidation of lactic acid by Cr(VI)was found to proceed in two measurable steps,both of which gave pyruvic acid as the primary product in the absence of Mn(II).2Cr(VI) 2CH3CHOHCOOH→2CH3COCOOH Cr(V) Cr(III)Cr(V) CH3CHOHCOOH→Cr(III) CH3COCOOH The observed kinetics was explained due to the catalytic and inhibitory effects of Mn(II)and Ce(IV)on the lactic acid oxidation by Cr(VI).The reactivity of lactic acid depends upon the experimental conditions.It acts as a two-or three-equivalent reducing agent in the absence or presence of Mn(II).It was examined that Cr(III)products resulting from the direct reduction of Cr(VI)by three-equivalent reducing agents.The oxidation of lactic acid follows the complex order kinetics with respect to [lactic acid].The activation parameters Ea,ΔH#,and ΔS# were calculated and discussed.     

氯化六咪唑合铁四水分子的结构表征和电化学性能研究(英)

The crystal structure of the title compound, [Fe(Im)₆]Cl₂·4H₂O, (Im=imidazole) was determined by X-ray analysis. The crystal structure consists of Fe(Im)₆²⁺ cation, two Cl^- anions and four non-coordinated water molecules. It crystallizes in the triclinic system, space group P1, with lattice parameters a=0.879 7(2) nm, b=0.906 8(2) nm, c=1.058 1(2) nm, α=75.35(3)°, β=83.20(3)°, γ=61.85(3)°, and Z=1; The Fe(Ⅱ) ion assumes centrosymmetric octahedron geometry with the FeN₆ core. Six imidazole molecules are coordinated to each iron(Ⅱ) ion through its tertiary nitrogen atom. The bond distances of Fe-N are in range of 0.212 8(1) nm to 0.220 4(1) nm. In the solid state, [Fe(Im)₆]²⁺, H₂O molecules and chlorine anions form three dimensional hydrogen bonds network which stabilized the crystal structure. Elemental analysis and electronic spectrum are in agreement with the structural data. The thermal gravity (TG) data indicate that thermal decomposition of the title compound takes place in five steps. In these cases, the residue may be Fe. From the cyclic voltammogram measurement in EtOH/H₂O, we know that electrode reaction was a quasi-reversible process. CCDC: 215335.     

新配合物[Cd(H2O)2(phen)2](PA)2的制备及晶体结构

The new compound was prepared by the reaction of Cd(ClO₄)₂·6H₂O,1,10-phenanthroline (phen)and picric acid (HPA)(ratio 1∶3∶2) in methanol-aqueous solution refluxing for 4 hours. The crystals used for X-ray analysis was obtained by slow evaporation of the solution at room temperature. The crystal compound is in triclinic with space group with a=1.1363(4)nm,b=1.2593(2)nm,c=1.3972(4)nm,α=93.97(2)?,β=100.84(3)?,γ=106.29(2)?,Z=2,V=1.8690(9)nm³,D_c=1.715g·cm^-3, μ(MoKα)=0.677mm^-1,F(000)=972,R=0.0907,wR=0.2240. In the complex, the Cd(Ⅱ) cation is octahedrally coordinated to two 1,10-phenanthroline ligands and two water molecules in cis disposition. As outer sphere, picrate anions are combined with inner by hydrogen bond and static electricity interaction.     

MULTIDENTATE LIGAND EXCHANGE KINETICS:REACTIONS OF AMINOCARBOXYLATO-FERRATE(Ⅲ) COMPLEXES WITH 4-(2-PYRIDYLAZO) RESORCINOL

The kinetics and mechanism of ligand substitution reactions of nitnlotriacetatoiron(Ⅲ),(Fe(NTA)],and N-(2-hydroxycthyl)-ethylencdiaminetriacetatoiron(Ⅲ),[Fe(HEDTA)],complexes with 4-(2-pyridylazo) resorcinol (Par) has been investigated at pH=9.0±0.02,I=0.1mol·l^-1 (NaClO₄,and temp.=25±0.1℃ and 30±0.1℃ respectively. The reaction has been studied spectrophotometrically at 496 nm. (λmax of Fe(Par)₂. In both reactions the final product was [Fe(Par)₂]^-. The values of second order rate constants for NTA and HEDTA exchange reactions are (10.0±0.8)×10¹¹·mol^-1·s^-1 and (2.7±0.1)×10^-1·mol^-1·s_-1 respectively. The reactions of NTA and HEDTA exchange were studied in the pH range 6-9.5 and 7-10.85 respectively. The rate of reacton of [Fe(NTA)] with HPar^- first increases with pH and then levels off. However,in the case of [Fe(HEDTA)] reaction,the rate increases monotonically with increase of pH in the specified range.     

以单环有机锡配合物为载体的水杨酸根阴离子选择电极的研究

Two new cyclic pentacoordinative organotin(Ⅳ) complexes, 2,4-dihydroxyacetophenone tribenzyltin(HAPTBT) and 2,4-dihydroxyacetophenone triphenyltin(HAPTPT) were synthesized and used as anion ionophore for PVC membrane electrode. The new electrodes exhibit specificity selectivity for salicylate. The electrode based on HAPTBT as a neutral carrier displays a highly potentiometric response to salicylate and an anti-Hofmeister selectivity sequence in the following order: Sal^- ＞ SCN^- ＞ I^- ＞ NO₂^- ＞ Br^- ＞ Cl^- ＞ ClO₄^- ＞ NO₃^- ＞ SO₄^2-. The electrode has the advantages of fast response, stability and reproducibility, simplicity. The response mechanism is discussed in view of UV spectroscopy technique. The results show that there are close relationship between the potentiometric response characteristics and structure of organotin(Ⅳ) complexes. The electrode was applied to medicine analysis with satisfactory results.     

N2O活化的Fe/ZSM-5表面活性氧的表征(英)

Temperature-programmed reduction (H₂-TPR) was employed to quantitatively characterize the active oxygen species generated from a high Fe-loading Fe/ZSM-5 catalyst exposed to N₂O at 250 ℃. [Fe-O-Fe]²⁺ dimer was determined as the active iron complex for N₂O decomposition to produce the active oxygen. Reduction of Fe³⁺ to Fe²⁺ by H₂ in the dimer and removal of OH^- groups from Fe²⁺ dimer by heating Fe/ZSM-5 to 700 ℃ were the prerequisites for the formation of this active Fe complex. A linear correlation with a slope of 1.0 between the amount of [Fe-O-Fe]²⁺ and that of active oxygen species was observed. Maximum amount of active oxygen species can be generated by reducing Fe/ZSM-5 catalyst with H₂ at the temperatures over 500 ℃ and then heating the resulting product in Ar to 700 ℃, followed by N₂O exposure at 250 ℃. The ratio of the total number of oxygen atoms (Ode) deposited by interaction of [Fe-O-Fe]²⁺ with N₂O to the amount of [Fe-O-Fe]²⁺ was 2. However, not all the deposited oxygen atoms were active oxygen (O_a); the ratio of O_a and O_de was 0.5. The iron dimer complex composing active oxygen is a five-atom ion [Fe₂O₃]²⁺; the most probable structure is as follows:     

二重穿插锰配合物Mn2(ADB)2(DMSO)4DMSO的溶剂热合成和结构研究

A novel Mn coordination polymers, Mn₂(ADB)₂(DMSO)₄·DMSO (H₂ADB=4,4′-azodibenzoic acid), has been prepared by solvothermal reaction and characterized by element analysis, IR spectra and single-crystal X-ray diffraction. The crystallographic data shows that the title complex crystallizes in monoclinic space group C2/c. Each Mn(Ⅱ) is six-coordinated to four O atoms from three ADB^2- ligands, two oxygen atoms from two DMSO molecule and forms distorted octahedral coordination geometry. The Mn(Ⅱ) dimers by the carboxyl groups of the ADB^2- ligands were interlinked together by the different carboxylate coordination modes of ADB^2- ligands, to yield scaffolds with 2D network with 4.8² topological structures. CCDC: 745678.     

Lu(Et2dtc)3(phen)的生成反应焓变、摩尔热容和恒容燃烧能测定

A ternary solid complex Lu(Et₂dtc)₃(phen) has been obtained from the reaction of hydrated lutetium chloride with sodium diethyldithiocarbamate (NaEt₂dtc), and 1,10-phenanthroline (o-phen·H₂O) in absolute ethanol. IR spectrum of the complex indicates that Lu³⁺ binds with sulfur atom in the Na(Et₂dtc)₃ and nitrogen atom in the o-phen. The enthalpy change of liquid-phase reaction of formation of the complex, Δ_rH_m^Ө (l), was determined to be (-32.821 ± 0.147 ) kJ·mol^-1 at 298.15 K by an RD-496 Ⅲ type heat conduction microcalormeter. The enthalpy change of the solid-phase reaction of formation of the complex, Δ_rH_m^Ө (s), was calculated to be (104.160 ± 0.168) kJ · mol^-1 on the basis of an appropriate thermochemistry cycle. The thermodynamics of liquid-phase reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, such as the activation enthalpy (ΔH_≠^Ө), the activation entropy (ΔS_≠^Ө), the activation free energy (ΔG_≠^Ө), the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A) and the reaction order (n), were obtained by combination the reaction thermodynamic and kinetic equations with the data of thermokinetic experiments. The molar heat capacity of the complex, c_m, was determined to be (82.23 ± 1.47) J·mol^-1·K^-1 by the same microcalormeter. The constant-volume combustion energy of the complex, Δ_cU, was determined as (-17 898.228 ± 8.59) kJ·mol^-1 by an RBC-Ⅱtype rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δ_cH_m^Ө, and standard enthalpy of formation, Δ_fH_m^Ө, were calculated to be (-17 917.43 ± 8.11) kJ·mol^-1 and (-859.95 ±10.12) kJ·mol^-1, respectively.     

高铁酸三钾钠的合成及其物理化学性质研究

首次提出了一种在浓的NaOH溶液中电合成0.83 mol•L^－1 Na₂FeO₄溶液进而高纯度合成固态K₃Na(FeO₄)₂的方法. 研究了合成条件, 并利用多种实验技术研究了该固态样品的性质. 实验表明, K₃Na(FeO₄)₂晶体在混合的NaOH-KOH溶液中, 其溶解-沉淀平衡曲线符合经验方程式: [Na^＋][K^＋]³[ ]^2.8＝1.4×10^－4 ([K^＋]≤1.01 mol•L^－1);在浓的KOH溶液中其溶解度与K₂FeO₄几乎一致. 和K₂FeO₄晶体不同, 所得K₃Na(FeO₄)₂晶体显示3个红外特征峰(787, 801～802和858～862 cm^－1)并具有P m1 (164)空间群的六方晶胞, 其粉末在Ar气中直到197 ℃才分解, 热稳定性低于K₂FeO₄.     

On the Origins of Some Spectroscopic Properties of “Purple Iron” (the Tetraoxoferrate(VI) Ion) and Its Pourbaix Safe-Space

In this work, the authors attempt to interpret the visible, infrared and Raman spectra of ferrate(VI) by means of theoretical physical-inorganic chemistry and historical highlights in this field of interest. In addition, the sacrificial decomposition of ferrate(VI) during water treatment will also be discussed together with a brief mention of how Rayleigh scattering caused by the decomposition of Fe^VIO₄²⁻ may render absorbance readings erroneous. This work is not a compendium of all the instrumental methods of analysis which have been deployed to identify ferrate(VI) or to study its plethora of reactions, but mention will be made of the relevant techniques (e.g., Mössbauer Spectroscopy amongst others) which support and advance this overall discourse at appropriate junctures, without undue elaboration on the foundational physics of these techniques.     

Kristallstruktur von Tl4Fe(CN)6

Crystal Structure of Tl₄Fe(CN)₆ Single crystals of Tl₄Fe(CN)₆ have been prepared for the first time and its crystal structure was determined. The pale yellow compound crystallizes in the triclinic space group P1 (No. 2) with the lattice parameters a = 726.6(1) pm, b = 797.4(8) pm, c = 1 336.0(1) pm, α = 104.7(9)°, β = 90.0(8)°, γ = 97.6(7)°, Z = 2 in a new structure type.     

REPARATION AND CHARACTERIZATION OF NEW SUPROFEN COMPLEXES OF Fe(III), Co(II) AND Ni(II)

Abstract

The preparation and properties of new complexes containing the biometals Fe(III), Co(II) and Ni(II) coordinated to the anti-inflammatory drug Suprofen are reported. The elemental analyses, together with the magnetic and thermal behavior and electronic, IR and Raman spectra, indicated the following stoichiometries for the latter two complexes: [M(Sup)₂(H₂O)₄]. For the Fe(III) complex, the generation of a dinuclear species may be proposed on the basis of ⁵⁷Fe Mössbauer measurements.     

Simultaneous determination of Fe(II) and Fe(III) by kinetic spectrophotometric H-point standard addition method

The H-point standard addition method (HPSAM) for simultaneous determination of Fe(II) and Fe(III) is described. The method is based on the difference in the rate of complex formation of iron in two different oxidation states with Gallic acid (GA) at pH 5. Fe(II) and Fe(III) can be determined in the range of 0.02–4.50 μg ml⁻¹ and 0.05–5.00 μg ml⁻¹, respectively, with satisfactory accuracy and precision in the presence of other metal ions, which rapidly form complexes with GA under working conditions. The proposed method was successfully applied for simultaneous determination of Fe(II) and Fe(III) in several environmental and synthetic samples with different concentration ratios of Fe(II) and Fe(III).     

Cyclic voltammetric study of the redox behavior of Fe(II)/Fe(III) systems forming during the oxidation of Fe(II) complexes with saccharin and with saccharin and 1,10-phenanthroline

The electrochemical redox behavior of Fe(II)/Fe(III) systems formed during the oxidation of complexes [Fe(C₇H₄NO₃S)₂(H₂O)₄] · 2H₂O (Fe-sac) and [Fe(C₇H₄NO₃S)₂(C₁₂H₈N₂] · 2H₂O (Fe-sac-phen) have been investigated using cyclic voltammetry in the aqueous medium. In the CVs one pair of well-defined cathodic and anodic peaks appear for the transfer of single electron in the Fe-sac complex. The peak potentials are much wider separated as compared with the free (uncoordinated) Fe(II)/Fe(III) system. The ΔE values demonstrate that the electrode process is irreversible. In the presence of secondary ligand, 1,10-phenanthroline (Fe-sac-phen complex), the redox behavior of iron complexes is quasireversible. The effect of pH on the redox behavior of iron system is studied in acetate buffer. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 12, pp. 1504–1509. The text was submitted by author in English     

Studies on the influence of various experimental conditions on electrochemical generation of ferrate(VI) in NaOH-KOH mixed electrolyte

Ferrate(VI) was prepared by electrooxidation in diaphragm electrolyzer with iron wire gauze as anode and NaOH-KOH mixed solution as electrolyte. The influences of various experimental conditions, such as the volume ratio of NaOH-KOH mixed electrolyte, temperature, current density, passivation of iron anode were investigated on ferrate current efficiency. Due to the low solubility of K₂FeO₄ in concentrated alkaline solution and the passivation of iron wire gauze anode, a highest current efficiency over 90% was obtained at 45°C and at a current density of 5 mA cm⁻² in mixed electrolyte with the volume ratio of NaOH: KOH equal to 6: 4. The result is superior to using NaOH and KOH as electrolyte respectively. In addition, polarization curves, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) were employed to further study the effects of synthesis conditions on ferrate(VI) in theory. Published in Russian in Elektrokhimiya, 2009, Vol. 45, No. 7, pp. 853–857. The article is published in the original.     

Fe(III) sequestering agents built on poly(ethylenimine) through crosslinkage of three molecules of a salicylate derivative preassembled by Fe(III) ion

Three molecules of 5-(bromoacetyl) salicylate ( 1 ) complexed to Fe(III) ion were crosslinked with poly(ethylenimine) (PEI) in DMSO by alkylation of amino groups of PEI with 1 , leading to the formation of Fe(Sal)₃PEI, a water-soluble polymer. Several other derivatives including the immobilized form were also prepared. Examination of the values of log K_f for the PEI derivatives indicated that each Fe(III) binding site in Fe(Sal)₃PEI contains three salicylate moieties. In addition, the log K_f revealed that the effective molarity (EM) of the salicylate groups contained in the Fe(III) binding site is ca. 1000M. The high EM value shows that the geometry of the coordination sphere is well conserved during the crosslinkage with PEI of 1 preassembled around Fe(III) ion. In view of the EM value and the pK_a values of salicylic phenols in apo(Sal)₃-PEI, the metal-free form, the three salicylate groups of each Fe(III) binding site appear to occupy proximal positions leading to effective cooperation in Fe(III) binding. Fast, strong, and selective binding of Fe(III) ion by the binding site comprising three salicylate moieties was demonstrated. In addition, rapid demetalation of the resulting complexes as well as chemical stability of the immobilized chelating agents built on PEI were achieved. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1197–1210, 1997     

An Fe(III) Complex with the Dianionic form of 2,6-Diacetylpyridine Bis(Acylhydrazone). The Crystal Structure of [Diaqua-2′,2′′′-(2,6-PyridinediyldiEthylidyne)Dioxamohydrazide]Iron(III) Perchlorate Trihydrate, [Fe(dapsox)(H2O)2]ClO4·3H2O

The title compound was prepared by a template synthesis from 2,6-diacetylpyridine, dioxamohydrazide and Fe(ClO₄)₃·6H₂O(mol ratio 1:2:1) in MeOH/H₂O(3:1) solution and its structure determined by single-crystal X-ray diffraction; triclinic, space group P1, a = 7.5186(7), b = 10.9730(9), c = 14.6110(10) Å, α = 95.866(1), β = 100.252(1), γ = 92.895(1), z = 2. The polydentate ligand is coordinated as a dianionic pentadentate while water molecules occupy apical positions in the structure. This is the first example of a monomeric, pentagonal bipyramidal structure of an Fe(III) complex with a dianionic bis(acylhydrazone) derivative of 2,6-diacetylpyridine.     

A contribution to 1-azapentadienylmetal chemistry: Si, Sn(II), Fe(II) and Co(II) complexes

Complexes of three related 1-azapentadienyl ligands [N(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R]⁻, abbreviated as L (R = Bu^t, R¹ = Me), L′ (R = Me = R¹), and L″ (R = Bu^t = R¹), are described. The crystalline compounds Sn(L)₂ (1), Sn(L′)₂ (2), [Sn(L′)(μ-Cl)]₂ (3) and [Sn(L″)(μ-Cl)]₂ (4) were prepared from SnCl₂ and 2 K(L), 2 K(L′), K(L′) and K(L″), respectively, in thf. Treatment of the appropriate lithium 1-azapentadienyl with Si(Cl)Me₃ yielded the yellow crystalline Me₃Si(L) (5) and the volatile liquid Me₃Si(L′) (6) and Me₃Si(L″) (7), each being an N,N,C-trisilyldieneamine. The red, crystalline Fe(L)₂ (8) and Co(L′)₂ (9) were obtained from thf solutions of FeCl₂ with 2 Li(L)(tmeda) and CoCl₂ with 2 K(L′), respectively. Each of 1-9 gave satisfactory C, H, N analyses; 6 and 7 (GC-MS) and 1, 2, 8 and 9 (MS) showed molecular cations and appropriate fragments (also 3 and 4). The ¹H, ¹³C and ¹¹⁹Sn NMR (1-4) and IR spectra support the assignment of 1-4 as containing Sn-N(SiMe₂R¹)-C(Bu^t)(CH)₃SiMe₂R moieties and 5-7 as N(SiMe₃)(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R molecules; for 1-4 this is confirmed by their X-ray structures. The magnetic moments for 8 (5.56 μ_B) and 9 (2.75 μ_B) are remarkably close to the appropriate Fe and Co complex [M{η³-N(SiMe₃)C(Bu^t)C(H)SiMe₃}₂]; hence it is proposed that 8 and 9 have similar metal-centred, centrosymmetric, distorted octahedral structures.