Synthesis, characterization and molecular structure of a novel asymmetrical half-sandwich binuclear iron carborane complex Cp ' Fe-2(2)(CO)(3)(Se2C2B10H10)

The half-sandwich methylcyclopentadlenyl iron carbonyl complex reacted with 1,2-dilithium diselenolate carborane Li2Se2C2B10H10 (1) which was produced by the insertion of element Se into 1, 2-dilithium carborane to give a half-sandwich binuclear iron carborane complex Cp'Fe-2(2)(CO) 3Se2C2B10H10 (3). X-ray structural analysis of complex 3 reveals that one of the iron atoms is chiral.

Assembly of the transition metal substituted polyoxometalates ZnW11M(H2O)O-39(n-) (M = Mn, Cu, Fe, Co, Cr, Ni, Zn) on 4-aminobenzoic acid modified glassy carbon electrode and their electrochemical study

Through layer-by-layer assembly, a series of undecatungstozincates monosubstituted by first-row transition metals, ZnW11M(H2O)O-39(n-) (M=Cr, Mn, Fe, Co, Ni, Cu. or Zn) were first successfully immobilized on a 4-aminobenzoic acid modified glassy carbon electrode surface. The electrochemical behaviors of these polyoxometalates were investigated. They exhibit some special properties in the films different from those in homogeneous aqueous solution. The Cu-centered reaction mechanism in the ZnW11Cu multilayer film was described. The electrocatalytic behaviors of these multilayer film electrodes to the reduction of H2O2 and BrO3- were comparatively studied.

Determination of rare and rare earth elements in soils and sediments by ICP-MS using Ti(OH)(4)-Fe(OH)(3) co-precipitation preconcentration

A method was developed for the determination of trace and ultratrace amounts of REE. Cd. In. Tl. Th. Nb, Ta. Zr and Hf in soils and sediments. With NaOH-Na2O2 as the flux. Ti(OH)(4)-Fe(OH)(3) co-precipitation as the preconcentration technique and inductively coupled plasma mass spectrometry (ICP-MS) for measurement, the whole procedure was concise and suitable for batch analysis of multi-element solutions. An investigation was carried out of the Ti(OH)(4)-Fe(OH)(3) co-precipitation system, and the results obtained showed that the natural situation of Ti tightly coexisting with Nb. Ta, Zr and Hf in geological samples plays a very important role in the complete co-precipitation of the four elements. The accuracy of this procedure was established using six Chinese soil and sediment certified reference materials (GSS and GSD). and the relative errors between the found and certified values were mostly below 10%.

仲辛基苯氧乙酸萃取Fe(Ⅲ)的性能

采用溶剂萃取法 ,研究了一种新型萃取剂———仲辛基苯氧乙酸 (CA— 12 )从盐酸介质中萃取Fe(Ⅲ )的性能。考察了萃取温度、平衡水相酸度、萃取剂初始浓度等对萃取的影响。实验结果表明 :分配比随平衡水相酸度的增加、萃取剂初始浓度的减小、温度的升高而减小。仲辛基苯氧乙酸从盐酸介质中萃取Fe(Ⅲ )的过程为放热过程 ,并计算得到其过程热ΔH =-2 .2 1kJ mol。

1,1 '-di(tert-butyl)metallocenium cations. The x-ray crystal structures of [M((C5H4Bu)-Bu-t)(2)]PF6 (M = Fe, Co) and [Co((C5H4Bu)-Bu-t)(2)](2)CoCl4

The hexafluorophosphate salts [Fe((C5H4Bu)-Bu-t)(2)]PF6 (1) and [Co((C5H4Bu)-Bu-t)(2)]PF6 (2) crystallize in isotypic structures with centrosymmetric cations which have a staggered (transoid) conformation of the exactly parallel ring Ligands (conformational angle tau = 180 degrees). The tetrachlorocobaltate salt, [CO((C5H4Bu)-Bu-t)(2)](2)CoCl4 (3), contains one almost eclipsed (tau = 140.4 degrees) and one almost staggered (tau = 101.4 degrees) cobaltocenium cation; in both cases, the cyclopentadienyl ring planes are slightly inclined (by alpha = 5.4 degrees and 4.1 degrees, respectively) to give more room to the tert-butyl substituents which are bent away from the metal in all three complexes 1 - 3.

Low-temperature oxidation of methane to form formaldehyde: role of Fe and Mo on Fe-Mo/SiO2 catalysts, and their synergistic effects

The partial oxidation of methane with molecular oxygen was performed on Fe-Mo/SiO2 catalysts. Iron was loaded on the Mo/SiO2 catalyst by chemical vapor deposition of Fe-3(CO)(12). The catalyst showed good low-temperature activities at 723-823 K. Formaldehyde was a major condensable liquid product on the prepared catalyst. There were synergistic effects between iron and molybdenum in Fe-Mo/SiO2 catalysts for the production of formaldehyde from the methane partial oxidation. The activation energy of Mo/SiO2 decreased with the addition of iron and approached that of the Fe/SiO2. The concentration of isolated molybdenum species (the peak at 1148 K in TPR experiments) decreased as the ion concentration increased and had a linear relationship with the selectivity of methane to formaldehyde. The role of Fe and Mo in the Fe-Mo/SiO2 catalyst was proposed: Fe is the center for the C-H activation to generate reaction intermediates, and Mo is the one for the transformation of intermediates into formaldehyde. Those phenomena were predominant below 775 K.

Gold-coated iron (Fe@Au) nanoparticles: Synthesis, characterization, and magnetic field-induced self-assembly

A unique reverse micelle method has been developed to prepare gold-coated iron (Fe@Au) nanoparticles. XRD, UV/vis, TEM, and magnetic measurements are utilized to characterize the nanocomposites. XRD only gives FCC patterns of gold for the obtained nanoparticles. The absorption band of the Fe@Au colloid shifts to a longer wavelength and broadens relative to that of the pure gold colloid. TEM results show that the average size of Fe@Au nanoparticles is about 10 nm, These nanoparticles are self-assembled into chains on micron scale under a 0.5 T magnetic field. Magnetic measurements show that the particles are superparamagnetic with a blocking temperature (T-B) of 42 K, At 300 K (above T-B), no coercivity (Hc) and remanence (M-r) is observed in the magnetization curve, while at 2K (below T-B) He and M, are observed to be 728 Oe and 4.12 emu/g, respectively, (C) 2001 Academic Press.

Hydrothermal synthesis of the two-dimensional coordination polymer {[Fe(phen)(OH)](bta)(0.5)}(n) (phen=1,10-phenanthroline, bta=benzene-1,2,4,5-tetracaboxylate)

The title two-dimensional coordination polymer was synthesised and characterised by X-ray diffraction analysis.

LaMAl_(11)O_(19)(M=Mg,Fe)的化学键性质和穆斯堡尔谱研究

利用复杂晶体化学键的平均能带模型研究了LaMAl11O19(M =Mg ,Fe)晶体的化学键性质。结果表明 ,La O键只有 3%的共价性 ,4f1格位却具有很强的共价特征。晶体中各格位共价次序为 :La O

Catalytic reduction of NO, by CO on hydrotalcites-derived mixed oxides CoAlM 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: hi) 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 H-2-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 were investigated respectively for supporting the mechanism.

Electrochemical behavior of a series of undecatungstozincates monosubstituted by first-row transition metals, ZnW11M(H2O)O-39(n-) (M = Cr, Mn, Fe, Co, Ni, Cu or Zn)

The electrochemical behavior of a series of undecatungstozincates monosubstituted by first-row transition metals, ZnW11M(H2O)O-39(n-) (M=Cr, Mn, Fe, Co, Ni, Cu or Zn), was investigated systematically and comparably in aqueous solutions by electrochemical and in situ UV-visible-near-IR spectroelectrochemical methods. These compounds exhibit not only successive reduction processes of the addenda atoms (W) in a negative potential range, but some of them also involve redox reactions originating from the substituted transition metals (M) such as the reduction of Fe-III and Cu-II at less negative potentials and the oxidation of Mn-II at a more positive potential. Some interesting results and phenomena, especially of the transition metals, were found for the first time. Moreover, possible reaction mechanisms are proposed based on the experimental results.

Preparation, charactreization, and catalytic properties of Co-M-Al (M = transition metal) mixed oxides derived from hydrotalcite-like compound

Hydrotalcite-like compounds (HTLcs) CoMAlCO3, where M stands for Cr, Mn, Ni, Cu, or Fe, were synthesized by coprecipitation. After calcination at 450 degrees C, they became mixed oxides with spinel-like structure. The mixed oxides were characterized by XRD, BET, chemical analysis and the adsorption of NO. The catalytic decomposition of NO and its reduction by CO were studied over these mixed oxides. The study showed that the catalytic activity for removal of NO, was very high. The reaction mechanism is proposed and the effects of d-electrons of the transition metals on catalytic activity are elucidated.

以水滑石类化合物为前体的Co-M-Al(M=过渡金属)复合氧化物对催化消除NO_x活性的研究

以共沉淀法制得的水滑石类化合物为催化剂前体,经焙烧可得到一系列尖晶石类化合物Co-M-Al[M=Cr,Mn,Fe,Ni,Cu;n(Co):n(M):n(Al)=3:1:1].通过XRD,比表面测定,化学分析,NO吸附等方法对其进行表征,测定了此系列催化剂对NO催化还原和催化分解的活性,结果发现此系列催化剂对消除NO具有很高的活性.同时对催化消除NO的机理及过渡金属离子中d轨道电子对催化活性的影响进行了一些探讨.

Study on the bond covalency and bond susceptibility in NdCr1-xMxO3 (M=Mn, Fe, Co)

Bond covalency, bond susceptibility and macroscopic linear susceptibility in NdCr1-xMxO3 (M=Mn, Fe, Co, 0.0 less than or equal to x less than or equal to 1.0) are investigated by complex chemical bond theory. The results indicate the bond covalencies are insensitive to the doping level. With the increasing doping level, the macroscopic linear susceptibilities increase for M=Mn, Fe, decrease for M=Co. The valence state of Cr can be strongly influenced by the properties of the doping ions.

金属-氨基多羧酸类配合物分子和晶体结构 Ⅰ.Na_2[Fe~Ⅲ(ida)_2]_2·3H_2O配合物的合成及结构测定

氨基多羧酸类配合物的配位数和结构不但与金属离子的半径、电荷和电子结构有关，而且还与氨基多羧酸类配体的形状和大小有关。本文报道了Ｎａ２［ＦｅⅢ（ｉｄａ）２］２·３Ｈ２Ｏ（ｉｄａ＝亚氨基二乙酸根）配合物的合成并测定了它的分子结构和晶体结构。具体结果如下：单斜晶系，Ｐ２１／ｃ空间群，ａ＝１５．６４８０（１０），ｂ＝１６．７８７０（１０），ｃ＝１０．３４７（２），β＝９０．７９０（１０）°，Ｖ＝２７１７．７（６）３，单位晶胞中的分子数为３，对于４７８９个独立的衍射点，它的Ｒ值为０．０３３３。其中两个配合物离子［ＦｅⅢ（ｉｄａ）２］－都是Ｎ和Ｎ顺位的变形八面体结构。由此可知具有对称电子结构（ｈｉｇｈ－ｓｐｉｎｄ５）的ＦｅⅢ与被看成是ｅｄｔａ（＝乙二胺四乙酸根）去掉了ＣＨ２－ＣＨ２的双ｉｄａ配体形成的配合物只能选择六配位八面体结构。