Influence of alloying platinum for the hydrogenation of chloronitrobenzene over PtM/ZrO2 catalysts with M=Cr, Mn, Fe, Co, Ni, Cu

Hydrogenation of chloronitrobenzene (CNB) over PtM/ZrO₂ (M= Cr, Mn, Fe, Co, Ni, Cu) catalysts has been studied in ethanol at 303 K and normal pressure. The results show that the hydrogenetion of CNB can be carried out over PtM/ZrO₂ catalysts. The order of the hydrogenation rates of CNB is p>m>o, and the yield of chloroaniline (CAN) is p>o>m. PtFe/ZrO₂ catalysts shows the highest catalytic activity on the hydrogenation of CNB. PtNi/ZrO₂ catalyst shows good yield of CNB to CAN, and 93.3 mol% for o-CAN, 98.0 mol% for m-CAN and 98.5 mol% for p-CAN, respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

MAPO-CHA(M=Mn,Fe,Co,Zn)系列过渡金属取代磷酸铝化合物的合成、结构与性质

在水热体系中, 以2-胺乙基哌嗪分解得到的二乙胺为模板剂, 合成了一系列具有CHA结构的过渡金属取代磷酸铝化合物MAl(PO₄)₂[(C₂H₅)₂NH₂](命名为MAPO-CHA, M=Mn, Fe, Co, Zn), 其M/Al原子比为1. 单晶结构分析表明, MnAPO-CHA晶体属于三方晶系, R3空间群, 晶胞参数a=1.4003(2)nm, c=1.5236(3) nm, V=2.5873(7) nm³, Z=9, 其无机骨架由Al(Mn)O₄四面体和PO₄四面体交替连接形成具有分子筛CHA的拓扑结构, 单质子化的二乙胺离子位于八元环孔道中. X射线粉末衍射分析表明, 这些化合物是同构的, 并均具有荧光性质, 其中, 化合物MAPO-CHA(M=Mn, Fe, Co)还具有弱的反铁磁交换作用.     

Density functional investigations of endohedral metallofullerenes TM@C24 (TM = Mn,Fe, Co,Ni, Cu,and Zn)

The theoretical investigations on TM@C₂₄ (TM = Mn, Fe, Co, Ni, Cu, and Zn) with different spin configurations have been performed by using the hybrid DFT‐B3PW91 functional in conjunction with 6‐31G(d) basis sets. The results show that the ground states of Fe@C₂₄ and Ni@C₂₄ are their spin triplet states, whereas the ground state of Co@C₂₄ is spin quartet state. Moreover, three Fe@C₂₄ isomers are favorable in energy. The HOMO and LUMO of Zn@C₂₄ indicates that there is no hybridization between Zn atomic orbitals and the C₂₄ cage orbitals. Natural population analysis shows that the charges always transfer from the TM atoms to the C₂₄ cage. In going from isolated TM atom to TM@C₂₄, the occupation of the 4s orbital is strongly reduced. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

MH~+(M=Fe,Co,Ni)催化二氧化碳的氢化反应

在密度泛函理论的B3LYP水平下计算了MH~+(M=Fe,Co,Ni)催化二氧化碳的氢化反应.研究表明,氢转移至C上要比转移至O上容易得多.探讨不同泛函方法对反应的影响,从CCSD(T)的计算结果可见,与Co H~+和Ni H~+相比,Fe H~+对H转移至C上的活性较高.电子结构分析表明,反应过程中氢转移为氢负离子转移.     

Generation and growth mechanism of metal (Fe, Co, Ni) nanotube arrays.

Nanotubes composed of layered or nonlayered materials have been synthesized through various methods, among which template-based electrodeposition technology provides a versatile technique for synthesizing one-dimensional nanostructured materials. However, the growth mechanism of nanotubes using the template method is seldom clarified. Herein, we present the systematic preparation of metal nanotube arrays and put forward the growth mechanism, termed current-directed tubular growth (CDTG), for template-based electrodeposition. There are competitive growth rates for metal atoms entering the crystal lattice, that is, v( parallel) (growth rate parallel to current direction) and v( perpendicular) (growth rate perpendicular to current direction). Metal nanotubes can be obtained at v( parallel)>v( perpendicular), while nanowires can be obtained at v( parallel) approximately v( perpendicular). The as-synthesized metal (Fe, Co, Ni) nanotubes are constructed from nonlayered materials, which are of body-centered cubic iron structure, hexagonal close packed cobalt structure, and face-centered cubic nickel structure, respectively. The CDTG mechanism is expected to have applications in designing and synthesizing other metal nanotubes and even compound nanotubes via template-based electrodeposition technology.     

Chemical catalytic vapor deposition (CCVD) synthesis of carbon nanotubes by decomposition of ethylene on metal (Ni, Co, Fe) nanoparticles

A simple method for producing unsupported nickel catalyst that can be used to synthesize multi-wall carbon nanotubes (MWNT) has been developed. The yield of purified MWNTs is about 1.8 g_mwnt/(g_cat×h).     

Scandium as an Element Intermediate between Rare Earth and Transition Metals in Intermetallics: Crystal Structures of Sc2Fe12P7, Sc3.6Fe10.4P7, and Sc2Co4P3. Other New Compounds with Zr2Fe12P7, Hf2Co4P3, Sc5Co19P12, and Yb6Co30P19 Type Structures

Abstract. Twenty five ternary phosphides crystallizing with four different but closely related structure types were prepared using elemental tin as a flux. Their lattice constants are reported. New compounds include Sc₂Fe₁₂P₇, Sc_3.6Fe_10.4P₇, Y₂Co₁₂P₇, and Hf₂T₁₂P₇ with T = Fe, Co, Ni. They crystallize with the hexagonal Zr₂Fe₁₂P₇ type structure, which was refined from single‐crystal X‐ray data of Sc_3.6Fe_10.4P₇: a = 944.1(1) pm, c = 363.4(1) pm, R = 0.041 for 719 unique structure factors and 23 variable parameters. The excess scandium atoms occupy one of the four iron sites of the Zr₂Fe₁₂P₇ type structure which has a higher coordination number than the other three iron sites. The two isotypic phosphides Sc₂Fe₁₂P₇ and Sc_3.6Fe_10.4P₇ do not form a continuous series of solid solutions. The new compounds Sc₂Co₄P₃ and Sc₂Ni₄P₃ are isotypic with Hf₂Co₄P₃. This hexagonal structure was refined for Sc₂Co₄P₃ from single crystal data: a = 1211.5(2) pm, c = 363.7(1) pm, R = 0.025 for 500 F_o and 38 variables. Other new compounds reported are Sc₅Ni₁₉P₁₂, Zr₅Fe₁₉P₁₂, Hf₅Fe₁₉P₁₂, and Hf₅Co₁₉P₁₂ which crystallize with Sc₅Co₁₉P₁₂ type structure, and the Yb₆Co₃₀P₁₉ type phosphides Sc₆Co₃₀P₁₉, Zr₆Co₃₀P₁₉, and Hf₆Co₃₀P₁₉. The structural relationships of these ternary phosphides are discussed with special attention to the environments of the transition metal atoms.     

Ternary Transition Metal Antimonides T5T' 1‐xSb2+x (T = Ti,Zr, Hf; T' = Fe,Co, Ni,Cu, Ru,Rh, Pd,Cd) with Nb5SiSn2 (Ordered W5Si3, Filled V4SiSb2) Type Structure

Fifteen new ternary antimonides T₅T' _1‐xSb_2+x were synthesized by reaction of the elemental components in an arc‐melting furnace. They crystallize with a tetragonal structure first reported for Nb₅SiSn₂ (space group I4/mcm, Z = 4.) A structure refinement from four‐circle X‐ray diffractometer data of Hf₅Fe_1‐xSb_2+x (a = 1086.0(1) pm, c = 550.1(1) pm, R = 0.033 for 270 structure factors and 18 variable parameters) showed deviations from the ideal occupancy for two atomic sites, resulting in the composition Hf_4.929(3)Fe_0.67(1)Sb_2.33(1). Structure refinements from X‐ray powder data resulted in the formula Ti₅Ni_0.45(2)Sb_2.55(2), while no deviation from the ideal composition was observed for Ti₅RhSb₂. The crystal structures of these compounds are discussed together with those of related binary and ternary compounds.     

Crystal Structure Refinement of M(NCNH)2 (M = Fe,Co) Based on Combined Neutron and X‐ray Diffraction Data

The crystal structures of Fe(NCNH)₂ and Co(NCNH)₂, isotypical with Ni(NCNH)₂, have been refined by means of combined X‐ray and neutron powder diffraction data (SPODI, FRM II). The lattice parameters are a = 6.6655(7), b = 8.7923(8), c = 3.3304(3) Å for Fe(NCNH)₂ and a = 6.5696(2), b = 8.8058(2), c = 3.2622(1) Å for Co(NCNH)₂ in the orthorhombic system Pnmm (no. 58). The positions of the hydrogen atoms have been clearly resolved.     

Theoretical and molecular modelling studies on organic transition metal complexes,II. Calculation of the stability constants of bidentate ligands in relation to theIrving-Williams order

The bidentate chelates of the transition elements Mn to Zn with salicylaldoxime, 8-hydroxyquinoline and 8-mercaptoquinoline have been constructed using molecular graphics and the stability constants derived from the calculated reaction enthalpies using an extended CNDO/2 method. The results generally follow theIrving-Williams order except for the mercaptoquinoline where large entropy effects are known to be present experimentally. The influence of substituents on the stability constant of salicylaldoxime is reflected in the calculated value particularly for electron-withdrawing groups.

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Theoretische und Molekülmodellierungs-Studien von organischen Übergangsmetallkomplexen, 2. Mitt.: Berechnung der Stabilitätskonstanten von zweizähnigen Liganden in Relation zurIrving-Williams-Ordnung

Zusammenfassung Die zweizähnigen Chelate der Übergangsmetalle Mn bis Zn mit Salicylaldoxim, 8-Hydroxychinolin und 8-Mercaptochinolin wurden unter Verwendung von molekulargraphischen Methoden und den Stabilitätskonstanten aus den mittels einer erweiterten CNDO/2-Methode ermittelten Reaktionsenthalpien konstruiert. Die Ergebnisse folgen generell derIrving-Williams-Ordnung, mit Ausnahme von 8-Mercaptochinolin, von dem bekannt ist, daß experimentell große Entropieeffekte auftreten. Der Einfluß von Substituenten auf die Stabilitätskonstanten der Salicylaldoximkomplexe spiegelt sich besonders für elektronenabziehende Gruppen in den berechneten Werten deutlich wider.

     

Mixed valency in the high-temperature phases of transition metal molybdates, A MoO4 ( A =Fe, Co, Ni)

Transition metal molybdates of the formulaAMoO₄ whereA=Fe, Co or Ni exhibit a first-order phase transition between 670K–970K. An investigation of the lowtemperature (lt) and high-temperature (ht) phases by x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, magnetic susceptibility and other physical methods shows that the phase transition is associated with a valence change of the typeA ²⁺+Mo⁶⁺αA ³⁺+Mo⁵⁺ in the cases of iron and cobalt molybdates. Contribution No. 311 from the Solid State and Structural Chemistry Unit.     

Catalytic reduction of NO_x by CO on hydro-talcites-derived mixed oxides Co AIM and MgAlM (M = Cr, Mn, Fe, Co, Ni, Cu)

Two series of mixed oxides, CoAlM and MgAlM (M= Cr, Mn, Fe, Co, Ni, Cu) , were prepared by calcining their corresponding hydrotalcite-like compounds (HTLc) . The ratio of Mg: Al: M (or Co: Al: M) was 3:1:1. The catalytic activity of all samples for the reaction of NO CO was investigated. The results showed that the activity of CoAlM was much higher than that of MgAlM. The structure and the property of redox were characterized by XRD and H2-TPR. The results indicated that only MgO phase was observed after calcining MgAlM hydrotalcites, and the transition metals became more stable. The spinel-like phase appeared in all of CoAlM samples after the calcination, and the transition metals were changed to be more active, and easily reduced . The activities of three series of mixed oxides CoAlCu obtained from different preparation methods, different ratio of Co:Al:Cu and at different calcination temperatures, were studied in detail for proposing the mechanism of reaction. The ability of adsorption of NO and CO     

MC2O4(M=Mn、Fe、Co、Ni、Cu、Zn)的热力学及其热分析动力学

用DSC、TGA技术分别在N₂气氛和O₂气氛下对MC₂O₄(M=Mn、Fe、Co、Ni、Cu、Zn)的脱水和分解过程作了热力学和动力学的研究. 在N₂气氛下, MC₂O₄•2H₂O(M=Mn、Fe、Co、Ni、Zn)脱水温度Tde和脱水焓ΔdeHm随原子序数Zre递增呈现明显的“二分组效应”；ΔdeHm在(96.46±7.00) kJ•mol^-1范围内波动；MC₂O₄•2H₂O (M=Mn、Fe、Ni)的分解温度Td随原子序数递增呈现良好的线性关系；且各草酸盐分解得到氧化物(CuC₂O₄生成Cu、CuO混合物)时, MC₂O₄(M=Co、Ni、Cu) 分解焓随原子序数增大也存在良好的线性关系. 各草酸盐除NiC₂O₄•2H₂O脱水过程和FeC₂O₄分解过程外, 其余各过程机理函数均为随机成核和随后成长型.     

MC_2O_4(M=Mn、Fe、Co、Ni、Cu、Zn)的热力学及其热分析动力学

用DSC、TGA技术分别在N2气氛和O2气氛下对MC2O4(M=Mn、Fe、Co、Ni、Cu、Zn)的脱水和分解过程作了热力学和动力学的研究.在N2气氛下,MC2O4·2H2O(M=Mn、Fe、Co、Ni、Zn)脱水温度Tde和脱水焓!deHm随原子序数Zre递增呈现明显的“二分组效应”;!deHm在(96.46±7.00)kJ·mol-1范围内波动;MC2O4·2H2O(M=Mn、Fe、Ni)的分解温度Td随原子序数递增呈现良好的线性关系;且各草酸盐分解得到氧化物(CuC2O4生成Cu、CuO混合物)时,MC2O4(M=Co、Ni、Cu)分解焓随原子序数增大也存在良好的线性关系.各草酸盐除NiC2O4·2H2O脱水过程和FeC2O4分解过程外,其余各过程机理函数均为随机成核和随后成长型.     

Solvothermal Synthesis of two 2‐D Thioantimonates(III) with Metal Complexes as Template Ions, [M(dap)3]Sb4S7 (M = Ni2+ and Co2+)

Two new thioantimonates [M(dap)₃]Sb₄S₇ (M = Ni²⁺ ( 1 ) and Co²⁺ ( 2 )) were synthesized under solvothermal conditions by the reaction of NiS (or Co metal), Sb and S in an aqueous solution of 1,2‐diaminopropane (dap). Compounds 1 and 2 are isostructural. The polymeric [Sb₄S₇^2?]_n anion is composed of two SbS₃ trigonal pyramids and two SbS₄ units. The SbS₃ and SbS₄ units are interconnected by corners and edges to build a 2‐D puckered layer with Sb₄S₄ and Sb₁₆S₁₆ heterorings. The apertures of the large Sb₁₆S₁₆ hetero‐rings are filled by two [M(dap)₃]²⁺ complex cations which serve as template ions. The band gaps of 2.44 eV for 1 and 2.43 eV for 2 have been estimated from optical absorption spectra.     

Determination of Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb in seawater using high resolution magnetic sector inductively coupled mass spectrometry (HR-ICP-MS)

A novel method, combining isotope dilution with standard additions, was developed for the analysis of eight elements (Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb) in seawater. The method requires just 12 mL of sample and employs an off-line pre-concentration step using the commercially available chelating resin Toyopearl AF-Chelate-650M prior to determination by high resolution inductively coupled plasma magnetic sector mass spectrometry (ICP-MS). Acidified samples were spiked with a multi-element standard of six isotopes (⁵⁷Fe, ⁶²Ni, ⁶⁵Cu, ⁶⁸Zn, ¹¹¹Cd and ²⁰⁷Pb) enriched over natural abundance. In addition, standard additions of a mixed Co and Mn standard were performed on sub-sets of the same sample. All samples were irradiated using a low power (119 mW cm⁻²; 254 nm) UV system, to destroy organic ligands, before pre-concentration and extraction from the seawater matrix. Ammonium acetate was used to raise the pH of the 12 mL sub-samples (off-line) to pH 6.4 ± 0.2 prior to loading onto the chelating resin. The extracted metals were eluted using 1.0 M Q-HNO₃ and determined using ICP-MS. The method was verified through the analysis of certified reference material (NASS-5) and the SAFe inter-comparison samples (S1 and D2), the results of which are in good agreement with the certified and reported consensus values. We also present vertical profiles of the eight metals taken from the Bermuda Atlantic Time Series (BATS) station collected during the GEOTRACES inter-comparison cruise in June 2008.     

电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰

采用电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰的含量。优化的试验条件如下:1柠檬酸溶液用量为2mL;2过氧化氢溶液用量为12mL;3称样量为0.100 0g;4氨水溶液用量为2mL。选择镍、铁、钴、锰的分析谱线分别为221.647,233.280,228.616,259.373nm。4种元素在一定的质量浓度范围内与其发射强度呈线性关系,方法的检出限(3s/k)在0.018~0.083mg·L-1之间。方法应用于标准物质(JBWY05901)的分析,测定值与认定值相符。方法用于生产样品和合成样品的分析,测定值的相对标准偏差(n=6)在0.72%~3.9%之间。     

$^{1}_{\infty}\rm [M^{II}(Py)_{2}(H_{2}O)_{n}(ADC)_{2/2}]$ mit MII = Fe,Co, Ni (n = 2) und MII = Cu (n = 1): Vier neue Koordinationspolymere mit dem Acetylendicarboxylat‐Dianion (ADC2−) als verbrückendem Liganden

with M^II = Fe, Co, Ni (n = 2) and M^II = Cu (n = 1): Four New Coordination Polymers with Acetylenedicarboxylate (ADC^2?) as Bridging Ligand By slow diffusion of pyridine (Py) into an aqueous solution of a respective metal salt and acetylenedicarboxylic acid (H₂ADC) single crystals of new coordination polymers of composition (M = Fe, Co, Ni; C2/c, Z = 4) ( 1 – 3 ) and (P2₁2₁2₁, Z = 4) ( 4 ) were obtained. In compounds 1 – 3 octahedral M^IIO₄N₂ units are connected via acetylenedicarboxylate anions to form chain‐like polymers. In compound 4 square pyramidal Cu^IIO₃N₂ units are found, which are also connected to chains by acetylenedicarboxylates. Thermoanalytical investigations on 3 show an abrupt mass loss of approx. 40 % above 130 °C, which points to a release of both pyridine ligands (calc.: 43 %). Thereafter, the sample decomposes continuously, which is confirmed by XRPD measurements, as an amorphous residue is found. Magnetic susceptibility measurements of 1 – 3 display paramagnetic behaviour in the temperature range 2‐300 K. While μ_eff of 3 (d⁸ configuration) with orbital singlet ground state is nearly temperature‐independent, 1 (d⁶) and 2 (d⁷) exhibit complicated μ_eff?T behaviour on account of a ligand‐field ground state derived from the cubic states ⁵T₂ and ⁴T₁, respectively. On the basis of a tetragonal ligand‐field model excellent adaptations are obtained with reasonable ligand‐field parameters. Exchange interactions between the magnetic ions are detected in no case.     

A combined computational & electrochemical exploration of the Ammi visnaga L. extract as a green corrosion inhibitor for carbon steel in HCl solution

Natural-based corrosion inhibitors have gained great research interest thanks to their low cost and higher performance. In this work, the chemical composition of the methanolic extract of Ammi visnaga umbels (AVU) was evaluated by gas chromatography (GC) coupled with mass spectrometry (MS) and applied for corrosion inhibition of carbon steel (CS) in 1.0 mol/L HCl using chemical and electrochemical techniques along with scanning electron microscope (SEM) and theoretical calculations. A total of 46 compounds were identified, representing 89.89% of the overall chemical composition of AVU extract, including Edulisin III (72.88%), Binapacryl (4.32%), Khellin (1.97%), and Visnagin (1.65%). Chemical (Weight loss) and electrochemical (potentiodynamic polarization curves (PPC), and electrochemical impedance spectroscopy (EIS)) techniques revealed that investigated extract can be used as an effective corrosion inhibitor for carbon steel in 1.0 mol/L HCl solution. At a low dose of 700 ppm, the inhibitory action of AVU extract reached an inhibition efficiency of 84 percent. According to polarization tests, the investigated extract worked as a mixed inhibitor, protecting cathodic and anodic corrosion reactions. The EIS test showed that upon the addition of AVU extract to HCl solution, the polarization resistance increased while the double layer decreased. SEM images showed a protected CS surface in the inhibited solution. Quantum chemical calculations by Density Functional Theory (DFT) for the main components confirmed the major role of heteroatoms and aromatic rings as adsorption sites. Molecular dynamics (MD) simulation was used to study the adsorption configuration of the main components on the Fe(1 1 0) surface. Outcomes from this study further confirmed the significant advantage of using plant-based corrosion inhibitors for protecting metals and alloys.     

The use of carbon nanofibers microcolumn preconcentration for inductively coupled plasma mass spectrometry determination of Mn,Co and Ni

Based on carbon nanofibers (CNFs) as a solid phase extraction adsorbent, a microcolumn preconcentration method coupled to inductively coupled plasma mass spectrometry (ICP–MS) was developed for the determination of trace elements (Mn, Co and Ni). The effect of various experimental parameters such as pH, sample flow rate and volume, elution solution and interfering ions on the retention of the studied ions have been investigated systematically. During all the steps of the experimental process, Mn, Co and Ni could be quantitatively sorbed on the microcolumn containing CNFs in the range of pH 6.0–9.0, and then eluted completely with 0.5 mol ml^− 1 HNO₃. A preconcentration factor of 150-fold was obtained. The detection limits for Mn, Co and Ni were 40, 0.4 and 8.0 pg ml^− 1, respectively, with relative standard deviations less than 6.0%. In order to validate the proposed method, two certified reference materials of human hair (GBW 07601) and mussel (GBW 08571), and water sample were analyzed with satisfactory results. The recoveries were between 95.0 and 114%.