PREPARATION AND CHARACTERIZATION OF CLUSTERS CONTAINING THE CoMRuS (M=Mo OR W) CORE

Abstract

The reaction of (μ₃-S)RuCo₂(CO)₉ with functionally substituted cyclopentadienyl tricarbonyl metal anions M(CO)₃(C₅H₄C(O)R) (M = Mo, W; R = OEt, CH₂CH₂COOMe) in THF under reflux gave new chiral skeleton clusters (μ₃-S)RuCoM(CO)₈(C₅H₄C(O)R) [M = Mo, R = OEt (1); M = W, R = OEt (2); M = Mo, R = CH₂CH₂COOMe (3); M = W, R = CH₂CH₂COOMe (4)]. These complexes were characterized by elemental analysis, IR and ¹H NMR spectra. The molecular structure of compound (1) was determined by single-crystal X-ray diffraction methods.     

Syntheses and crystal structures of butterfly M2Te2 complexes of molybdenum and tungsten with functionalized cyclopentadienyl ligands

Reactions of singly-bonded dinuclear complexes [(η⁵-CH₃O₂CC₅H₄)₂M₂(CO)₆] (I, M?=?Mo; II, M?=?W) with the diarenylditelluride [4-CH₃C₆H₄Te]₂ in refluxing toluene for 4–6?h afforded dinuclear complexes 1 and 2 trans/ae-[(η⁵-RC₅H₄)₂M₂(CO)₄(μ-ArTe)₂] (Ar?=?4-CH₃C₆H₄Te). Complexes 1 and 2 were also synthesized by reactions of triply-bonded dinuclear complexes [(η⁵-CH₃O₂CC₅H₄)₂M₂(CO)₄] (III, M?=?Mo; IV, M?=?W) with [4-CH₃C₆H₄Te]₂ in refluxing toluene for 1?h. Both complexes have been characterized by elemental analysis, ¹H NMR, ¹³C NMR and IR spectroscopy and X-ray diffraction. Preliminary low-temperature NMR experiments on complexes 1 and 2 have revealed that in solution each complex goes through a rapid inversion of the butterfly four-membered ring M₂Te₂.     

Microwave synthesis,structure, and properties of molybdophosphate compounds

Two compounds of disphosphopentamolybdate(VI) with the formulae (C₄H₁₄N₂O)₃- [P₂Mo₅O₂₃]?·?3H₂O (1) and (C₄H₁₄N₂O)₅(NH₄)₂[P₂Mo₅O₂₃]₂?·?5H₂O (2) have been synthesized by a simple, fast and efficient microwave method, and their crystal structures and spectroscopic properties have been studied. The heteropoly anion [P₂Mo₅O₂₃]^6? has a known structure built of five MoO₆ octahedra and two PO₄ tetrahedra. The MoO₆ octahedra form a pentagonal ring by sharing four edges and one corner and the PO₄ tetrahedra are attached to one side of the ring by three oxygen atoms. The most interesting feature of compound 1 is its extensive framework based on a one-dimensional zigzag chain. In compound 2, a more extensive and complicated framework of hydrogen bonds joins the anions, organic cations and water molecules together.     

磺基水杨酸-溴邻苯三酚红-溴化十六烷基吡啶分光光度法测定食品中钼的研究

研究了在pH5.6的HAc NaAc缓冲溶液中,溴化十六烷基吡啶(CPB)存在下,钼(Ⅵ)与溴邻苯三酚红及磺基水杨酸形成多元配合物的显色反应,建立了测定食品中微量钼的新方法。该配合物的最大吸收波长为λmax=620nm,表观摩尔吸光系数ε620=1.84×105L·mol-1·cm-1。钼(Ⅵ)浓度在0～0 80μg mL范围内符合比尔定律。应用于粮食作物中微量钼的测定,相对标准偏差小于4 8%,回收率为95.2%～100.5%。     

新的极谱催化体系连续测定岩溶地下水中钨和钼

钨、钼-二苯基乙醇酸-2,2′-联吡啶-钛铁试剂连测体系还未见报道。本文提出了在0.05mol/L的硫酸中,钨与二苯基乙醇酸,2,2′-联吡啶的络合物在-0.79V(vs.SEC)产生一个极其灵敏的极谱催化波,测定完钨后,加入少量钛铁试剂测定钼。钼于-0.20V(vis.SEC)处产生极灵敏的阴极化导数波,波形尖锐对称,易于测量。采用此种连测体系,钨钼的灵敏度都可满足要求,钨和钼的检出限分别为0.004、0.01μg/L。确定最佳条件和拟定了不经分离富集直接测定岩溶地下水中痕量钨和钼的方法。此外还对极谱波性质进行了探讨,讨论了阴、阳离子表面活性物质对极谱催化波的作用机理。     

极谱法快速检测地球化学勘查样品中的钨和钼

采用质量比3+1的NaOH+KOH混合熔剂熔矿,固定体积的提取溶剂,医用注射器吸取澄清溶液,省去调节酸度过程,一次注射加入极谱底液,催化极谱法测定地球化学勘查样品中的钨和钼。方法检出限为W0.30μg/g、Mo0.49μg/g。方法精密度(RSD,n=12)为W5%—11%、Mo5%—26%。方法准确度(RE,n=12)为W0.5%—18%、Mo1%—31%。     

ZnO/MoO3 mixed oxide nanotube: A highly efficient and stable catalyst for degradation of dye by air under room conditions

As a continuation of our work to develop catalysts with high activity for catalytic air wet oxidation process under mild conditions, degradation of wastewater containing 0.3 g/L Safranin-T (ST) by air oxidation over ZnO/MoO₃ nanotube catalyst was studied. It was found the decolorization efficiency and the chemical oxygen demand (COD) removal of ST reached above 98% and 95%, respectively, within 18 min at room temperature and atmospheric pressure. And the organic pollutants were totally mineralized to simple inorganic species such as HCO₃⁻, Cl⁻ and NO₃⁻, while the total organic carbon (TOC) decreased 99.3%. The structure and morphology of the catalyst after ten cycling runs showed that the catalyst was stable under such operating condition and the leaching test showed negligible leaching effect. This ZnO/MoO₃ nanotube is proved to be an active and stable heterogeneous catalyst in CWAO of ST under extremely mild conditions.     

Tunable magnetic properties of arrays of Fe(1 1 0) nanowires grown on kinetically grooved W(1 1 0) self-organized templates

We report a detailed magnetic study of a new type of self-organized nanowires discussed briefly previously [B. Borca et al., Appl. Phys. Lett. 90 (2007) 142507]. The templates, prepared on sapphire wafers in a kinetically limited regime, consist of uniaxially grooved W(1 1 0) surfaces, with a lateral period here tuned to 15 nm. Fe deposition leads to the formation of (1 1 0) 7 nm-wide wires located at the bottom of the grooves. The effect of capping layers (Mo, Pd, Au, Al) and underlayers (Mo, W) on the magnetic anisotropy of the wires was studied. Significant discrepancies with figures known for thin flat films are evidenced and discussed in terms of step anisotropy and strain-dependent surface anisotropy. Demagnetizing coefficients of cylinders with a triangular isosceles cross-section have also been calculated, to estimate the contribution of dipolar anisotropy. Finally, the dependence of magnetic anisotropy with the interface element was used to tune the blocking temperature of the wires, here from 50 to 200 K.     

强碱性阴离子交换树脂分离富集土壤中的钼

研究了以强碱性阴离子交换树脂为固定相的离子交换色谱法分离富集土壤中钼,实现了钼与其他常见金属元素离子的选择性分离,富集在色谱柱上的钼以0.5mol.L^-1NH4NO3＋2mol.L^-1HNO3洗脱并用富氧火焰原子吸收光谱法进行测定,钼的回收率为99%—101.3%。     

Self-interstitial configuration in molybdenum studied by modified analytical embedded atom method

The stability of various atomic configurations containing a self-interstitial atom (SIA) in a model representing Mo has been investigated using the modified analytical embedded atom method (MAEAM). The lattice relaxations are treated with the molecular dynamics (MD) simulation at absolute zero of temperature. Six relatively stable self-interstitial configurations and formation energies have been described and calculated. The results indicate that the [111] dumbbell interstitial S₁₁₁ has the lowest formation energy, and in ascending order, the sequence of the configurations is predicted to be S₁₁₁, C, S₁₁₀, T, S₀₀₁ and O. From relaxed displacement field up to the fifth-NN atoms of six configurations, we know that the relaxed displacements depend not only on separation distances of the NN atoms from the defect centre but also strongly on the direction of the connected line between the NN atoms and the defect centre. The equilibrium distances between two nearest atoms in the core of the S₁₁₁, C, S₁₁₀, T, S₀₀₁ and O configurations are 0.72a, 0.72a, 0.71a, 0.72a, 0.70a and 0.70a, respectively.