The Cadmium Oxide Route to Alkali Metal Oxometallates with Uncommon Structural Features

The aim of this research report is to give an introduction to a specific solid state reaction applied in the field of alkali metal rich transition metal compounds. The approach is an explorative investigation of the oxidation of transition metals with CdO in the presence of alkali metal oxides and / or compounds with complex anions such as Na₂SO₄. Thereby, a range of unusual compounds have been obtained and structurally characterized. In particular, low valences and uncommon coordination numbers (C.N.) of the late 3d transition metals, as well as interesting varieties in the anionic part of the structures are accessible. The presented examples were selected mainly in order of their inherent aspects concerning the reactivity, structural features or electronic structures.     

燃烧过程中碱/碱土金属对重金属迁移转化影响的研究进展

碱/碱土金属广泛存在于各种固体燃料中，在燃烧过程中碱/碱土金属与燃料中重金属及其他矿物发生复杂的物理化学反应，从而影响重金属的迁移和转化。本研究主要介绍了碱/碱土金属对As、Se、Pb和Cr四种重金属迁移转化的影响规律，包括碱金属和碱土金属对重金属迁移转化的影响，颗粒物团聚与黏结对重金属排放的影响三个方面。碱/碱土金属能够抑制重金属的挥发：碱金属与Cl元素的结合，降低了PbCl₂的生成；碱金属的存在有利于提升高岭土对Pb的吸附效率；碱/碱土金属可以与As和Se形成稳定的化合物。但同时需要注意碱/碱土金属与Cr的部分结合产物中，Cr以六价态存在，具有较高的毒性。碱/碱土金属对于团聚现象发生，分别起到了促进和抑制作用，适当含量的碱金属有利于减少重金属的释放。通过总结碱/碱土金属对重金属迁移转化的影响规律，以期为降低重金属的危害提供思路。     

二元合金Ag_(50)Rh_(50)从液态到非晶的分子动力学计算

本文对贵重金属银铑合金Ag50Rh50的液态结构和激冷过程进行了分子动力学模拟研究原子间作用势采用紧束缚势模拟在施加了周期性边界条件的常压状态下进行。采用了偶关联函数、键对分析技术和键取向序参数以分子动力学模拟计算方法揭示了Ag50Rh50的液态结构存在原子偏聚特征以及在快速凝固过程形成原子偏聚的不均匀非晶并与同族过渡金属进行了非晶形成能力的比较。     

Solution extraction of transition and post-transition heavy and precious metals by chelate and macrocyclic ligands

This review focuses on compounds and methods that can be used for the extraction and separation from solution of two classes of elements that we define as heavy metals and precious metals. These elements are often targeted because they are toxic, costly, and their coordination chemistry has already been well studied, and because there is a need to develop methods of economically extracting, separating and recovering them from waste sites. This review outlines possible strategies that can be used, and reviews the present literature regarding the available methods for their extraction.     

Monitoring and statistical evaluation of heavy metals in airborne particulates in Cairo, Egypt

Airborne particulate material was monitored as total suspended particles and particulate matter less than 10 μm at selected sites in Cairo. The selected sites represent heavily industrial and industrial–residential areas of Cairo, Egypt. The filters were further analyzed for lead, cadmium, zinc and nickel using ion chromatography. The chosen method was modified to improve resolution and decrease the retention time. The data obtained were treated statistically using one-way analysis of variance and correlated with the anthropological and industrial activities of the sites. The concentrations of the heavy metals are studied in terms of particle size, time dependence, and safety.     

Utilization of olive pomace in nano MgO modification for sorption of Ni(II) and Cu(II) metal ions from aqueous solutions

Magnesium oxide nanoparticles were synthesized and modified by olive pomace (NMOOP700) as a novel sorbent and characterized using Fourier Transform Infrared Spectra, Scanning Electron Microscope, Transmission Electron Microscope, X-ray Diffraction, Differential Thermal Analysis and Thermal Gravimetric Analysis. Sorption of Cu (II) or Ni (II) ions were achieved taking into account important parameters including initial pH of the medium, contact time, initial metal ion concentration and temperature. A comparative study between Magnesium oxide nanoparticles and NMOOP700 material for the sorption of Cu (II) or Ni (II) ions was implemented. The obtained data revealed that the sorption process is significantly improved using NMOOP700. The monolayer capacity of Ni (II) and Cu (II) metal ions on NMOOP700 at pH 5 were found to be 149.93 ± 4.4 and 186.219 ± 6.3 mg/g, respectively. Findings of the present work highlight the potential use of NMOOP700 as a novel and effective sorbent material for the removal of Cu (II) or Ni (II) ions from the liquid phase.     

ChemInform Abstract: Electronic Structure Calculations for the Ternary Intermetallic Compounds A2MX and AMX2 (A: Li; M: Rh,Pd, Ir,Pt; X: Al,Ga, In) Using Density‐Functional Theory.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Response of polyacrylamide—acyclic poly(oxyethylene)-coated ion-selective electrodes to alkali and alkaline earth metal ions in propylene carbonate and its thermodynamic application

The response of ion-selective electrodes with a membrane of polyacrylamide (PAA) coupled to acyclic poly(oxyethylene) neutral carriers to lithium, sodium, potassium, magnesium and barium ions in propylene carbonate (PC) was investigated. Tetraethylene glycol monododecyl ether (POE4) and hexaethylene glycol monododecyl ether (POE6) were used as the acyclic poly(oxyethylene). Both the PAA-POE4 and the PAA-POE6 electrodes showed a more rapid dynamic response in PC than that in acetonitrile. Nernstian responses to lithium, magnesium and barium ions were obtained with the PAA-POE4 electrode. The selectivity coefficients, logk_Ba²⁺,M^x+, for lithium, sodium, potassium and magnesium ions vs. barium ion obtained in PC with the PAA-POE4 electrode were 3.6, 0.23, 0.02 and 1.1, respectively. The PAA-POE4 electrode was applied to obtain the successive formation constants of the barium ion in PC with N, N-dimethylacetamide (DMA). From the successive formation constants obtained in PC-rich solutions, the Gibbs free energies of transfer of the barium ion from PC to DMA and to PC-DMA mixtures were calculated. The electrode was also used to obtain directly the Gibbs free energies of transfer of the barium ion from PC to PC-DMA mixtures. The calculated values of the free energies were in good agreement with the values obtained experimentally, suggesting that the electrode responded to variations in solvation energy for the barium ion.     

Separation and detection of common mono- and divalent cations by ion chromatography with an ODS column and conductivity/UV detection

The retention and detection behavior of common mono- and divalent cations (M⁺, alkali metal (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) and ammonium ions (NH₄⁺); M²⁺, alkaline earth metal ions (Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺) was examined using an ODS column (150×4.6 mm I.D.) and conductivity (CD)/UV detection. The results obtained were as follows: (1) for M⁺, the mobile phase, 0.1 mM sodium dodecyl sulphate (SDS)+10 mM HNO₃ and indirect CD detection were effective. (2) Addition of Ce(III) in the mobile phase accelerated the elution of both M⁺ and M²⁺. The separation of above 10 cations on an ODS column was achieved for the first time without any coelution of cations and disturbance by system peak. Addition of higher SDS resulted in good separation of M⁺ and M²⁺ with longer retention times. CD detection was possible for M⁺ and M²⁺ and UV detection for M²⁺. (3) For M²⁺, the mobile phase, 0.8 mM Ce(III)+0.1 mM SDS+1 mM HNO₃ and indirect UV detection were effective. The IC methods were applied to real samples.     

水溶性环境友好型防锈剂的研制

为了克服目前水溶性防锈剂防锈效果差、含亚硝酸盐等有毒物质,以及成本较高、污染较严重等缺点,本文以三乙醇胺、苯甲酸钠、四硼酸钠、碳酸钠、葡萄糖酸钠为主要原料研制出一种水溶性环保防锈剂。通过正交试验分析了各组分用量对防锈性能的影响,优选出最佳方案。采用一系列实验方法对研制的防锈剂性能进行了评价,结果表明该新型防锈剂不仅对黑色金属如铸铁、钢,而且对多种有色金属,如铜、铝、镁等均有较好的防锈效果。     

二元合金Ag50Rh50从液态到非晶的分子动力学计算

本文对贵重金属银铑合金Ag50Rh50的液态结构和激冷过程进行了分子动力学模拟研究,原子间作用势采用紧束缚势,模拟在施加了周期性边界折常压状态下进行。采用了偶关联函数,键对分析技术和键取向序参, 分子动力学模拟计算方法揭示了Ag50Rh50的液态结构存在原子偏聚特征以及在快速凝固过程形成原子偏聚的不均匀非晶,并与同族过渡金属进行了非晶形成能力的比较。     

ChemInform Abstract: Bonding,Structure, and Stability of Ternary Hydrides A2MH2 (A: Li,Na; M: Pd,Pt).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Recent achievements in the synthesis and characterization of metal hexafluorantimonates and hexafluoroaurates

The efforts to prepare new MSbF₆/MSb₂F₁₁ (A = In, Cu, Au, Hg) compounds were partly successful. Reaction between InBF₄ and excess SbF₅ in anhydrous hydrogen fluoride (aHF) yields a mixture of InF₃·3SbF₅ and unidentified SbF₃·xSbF₅. The attempts to synthesize MSbF₆/MSb₂F₁₁ salts (A = Au, Hg) by controlled reduction of Au(SbF₆)₂ or Hg(SbF₆)₂ solutions in aHF/SbF₅ by elemental hydrogen, resulted in the precipitation of metallic Au or Hg₂(Sb₂F₁₁)₂. In the reaction of metallic Cu and deficit SbF₅, the synthesis of CuSbF₆ was achieved. CuSbF₆, like CuAsF₆, is a rare example of a Cu(I) compound in a pure fluorine environment.Vibrational spectra of M(II) hexafluoroantimonates (M = Ni, Fe, Co, Cu, Cr, Pd, Ag) were reinvestigated. It was found that many of them originally assigned to M(SbF₆)₂ compounds, belong to their mixtures with oxonium salts H₃OM(SbF₆)₃, H₃OSbF₆, and/or H₃OSb₂F₁₁.Reactions were studied between MF₂/2AuF₃ (M = Ni, Cu, Ag, Zn, Cd and Hg) and KrF₂ or UV-irradiated elemental fluorine in aHF as solvent at room temperature. On the basis of mass balances, Raman spectroscopy and X-ray powder diffraction analysis it can be concluded that the isolated solids have structures that can be considered in terms of an M(AuF₆)₂ formulation. Previously reported syntheses and characterization of M(AuF₆)₂ (M = Mg, Ca, Sr, Ba) were reinvestigated. In the case of M = Ba two different Au⁻F₆ salts were isolated.Raman spectra of the majority of synthesized metal hexafluoroaurates (M = Ni, Cu, Ag, Zn, Cd, Hg, Mg and Ca) show more bands than expected for regular Au⁻F₆ anion, indicating that the salts obtained exhibit relatively strong cation-anion interactions. The Raman spectra of the remaining Sr and Ba salts show the presence of more regular Au⁻F₆ octahedra, indicating weak cation-anion interactions.     

A perturbed hard-sphere equation of state for liquid metals

A perturbed hard-sphere equation of state, developed previously for liquid alkali metals and liquid refractory metals, has been applied for PVT calculation of some pure liquid metals including alkaline earth metals, tin, lead, antimony, bismuth, and rubidium over a wide range of temperatures and pressures. Two temperature-dependent parameters appear in the equation of state, which are universal functions of the reduced temperature, i.e. two scale parameters are sufficient to calculate the temperature-dependent parameters. The scaling parameters can be easily obtained by employing a corresponding-states principle based on a Lennard-Jones potential energy function. Employing the present equation of state, the liquid densities of aforementioned metals at temperatures ranging from the melting point to 2000?K and at pressures ranging from vapour pressure up to 40,000?bar have been calculated and compared with experimental data. The average absolute deviation in predicted densities compared with experimental data is 1.54%.     

Investigations into cluster formation with alkyl-tethered bis-calix[4]arenes

Abstract

Calix[4]arenes are versatile ligands capable of forming a wide range of cluster motifs when reacted with 3d, 4f or 3d/4f metal ions. Synthetic modification at the calix[4]arene methylene bridge offers a unique opportunity to explore cluster formation with these alternative building blocks. Here, we present the synthesis of a range of bis-calix[4]arenes that are tethered by alkyl chains, as well as exploratory structural studies into cluster-forming reactions. Single crystals were formed in four cases, and from the X-ray structures elucidated it is possible to conclude that sufficiently long alkyl tethers allow for the formation of established cluster topologies without disruption to the core coordination chemistry.     

Baeyer-villiger oxidation and oxidative cascade reactions with aqueous hydrogen peroxide catalyzed by lipophilic li[b(c(6) f(5) )(4) ] and ca[b(c(6) f(5) )(4) ](2)

Efficient and selective: Two lipophilic catalysts were used for Baeyer-Villiger (BV) oxidations to give lactones in high yields. Cascade reactions involving this BV oxidation were used to selectively obtain either unsaturated carboxylic acids or hydroxylactones in high yields from β-silyl cyclohexanones.     

Nanocatalysts Fabricated by a Dealloying Method

Two types of nanomaterials with different morphologies are described in this article: nanoporous metals and titanate nanowires. Both materials are fabricated by a dealloying method. In the former case, the catalytic properties of nanoporous gold and palladium are exemplified by many chemical transformations. The reactions proceed without any support, stabilizer, or ligands. The catalyst can be easily recovered by a simple separation process and reused many times without significant loss of catalytic activity. In the latter case, the dealloying of Ti–Al alloy is described as a new fabrication method for producing ultrafine titanate nanowires. This method does not require high‐temperature conditions, which is advantageous for the construction of fine structures. The key to this process is achieving a fine dispersion of intermetallic TiAl₃ nanocrystals in the Al matrix in the mother alloy. The resulting nanowires exhibit remarkable Sr²⁺ ion‐exchange properties.     

Ion Exchange in Hydrometallurgical Processing: An Overview and Selected Applications

Ion exchange has traditionally been employed for the purification of water and the removal of metal contaminants from dilute waste streams. More recently, its use in removing trace metallic impurities from hydrometallurgical process streams (with typical background metal concentrations of 50–100 g/L) has increased substantially. It is also used as a primary recovery and concentration unit operation for certain commodities, where both technical and cost advantages become apparent for complex flow sheets. This overview discusses selected modern applications of ion exchange in hydrometallurgical processes for uranium, precious metals, copper, cobalt, nickel and zinc, and identifies some opportunities for the future.     

Method of Continuous Variations: Applications of Job Plots to the Study of Molecular Associations in Organometallic Chemistry

Applications of the method of continuous variations (MCV or the Method of Job) to problems of interest to organometallic chemists are described. MCV provides qualitative and quantitative insights into the stoichiometries underlying association of m molecules of A and n molecules of B to form A_mB_n . Applications to complex ensembles probe associations that form metal clusters and aggregates. Job plots in which reaction rates are monitored provide relative stoichiometries in rate‐limiting transition structures. In a specialized variant, ligand‐ or solvent‐dependent reaction rates are dissected into contributions in both the ground states and transition states, which affords insights into the full reaction coordinate from a single Job plot. Gaps in the literature are identified and critiqued.