Large heteropolymetalate complexes formed from lanthanide (Y, Ce, Pr, Nd, Sm, Eu, Gd), nickel cations and cryptate [As4W40O140]: synthesis and structure characterization

A new family of heteropolytungstate complexes (NH₄)₂₁[Ln(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]·xH₂O(Ln=Y, Ce, Pr, Nd, Sm, Eu, Gd) were prepared by the reaction of Na₂₇[NaAs₄W₄₀O₁₄₀]·60H₂O with NiCl₂·6H₂O and Ln(NO₃)₃·xH₂O at pH≈4.5. The crystal structures of (NH₄)₂₁[Gd(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]·51H₂O was determined by X-ray diffraction analysis and element analysis. The compound crystallizes in the monoclinic space group P2₁/n with a=19.754(3), b=24.298(4), c=39.350(6) Å, β=100.612(3)°, V=18564(5) ų, Z=2, R1(wR₂)=0.0544(0.0691). The central site S1 and two opposite sites S2 of the big cyclic ligand [As₄W₄₀O₁₄₀]²⁸⁻ are occupied by one Ln³⁺and two Ni²⁺, respectively, each site supply four O_d coordinating to metal ion, another one water molecule and other five water molecules coordinate, respectively, to Ni²⁺and Ln³⁺. Polyanion [Ln(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]²¹⁻ has C_2v symmetry. IR and UV–vis spectra of [NaAs₄W₄₀O₁₄₀]²⁷⁻ of the title compounds are discussed.     

Reaktionen von MoNCl3 und WNCl3 mit elementarem Fluor. Kristallstrukturen von [MoO2F2(THF)2] und [WF4(NCl)(CH3CN)]

Reactions of MoNCl₃ and WNCl₃ with Elemental Fluorine. Crystal Structures of [MoO₂F₂(THF)₂] and [WF₄(NCl)(CH₃CN)] The nitrido chlorides MoNCl₃ and WNCl₃ as well as WCl₄(NCl) react with elemental fluorine forming the N-chloro imido complexes MoF₄(NCl) and WF₄(NCl), which were characterized by IR spectroscopy. With tetrahydrofurane MoF₄(NCl) reacts to give [MoF₄(NCl)(THF)], which in THF solution slowly converts into [MoO₂F₂(THF)₂]. From WF₄(NCl) with acetonitrile the complex [WF₄(NCl)(CH₃CN)] is obtained. Both donor acceptor complexes were characterized by crystal structure determinations. [MoO₂F₂(THF)₂] : Space group P2₁/n, Z = 4, structure solution with 1823 unique reflections, R = 0.033 for reflections with I > 2σ(I). Lattice dimensions at ?40°C: a = 636.2, b = 1119.5, c = 1625.2 pm; β = 93.92(1)º. The compound has a monomeric molecular structure with the fluorine atoms in trans-position to one another and with the oxygen atoms of the THF molecules in trans to the oxo ligands. [WF₄(NCl)(CH₃CN)] : Space group P2₁/m, Z = 2, structure solution with 1119 unique reflections, R = 0.038 for reflections with I > 2σ(I). Lattice dimensions at 20°C: a = 511.7, b = 714.9, c = 1002.5 pm; β = 102.59(10)º. The compound has a monomeric molecular structure in which the nitrogen atom of the acetonitrile molecule coordinates in trans-position to the N-chloro imido group W?N? Cl. The structural parameters of this group are WN = 172.2 pm, NCl = 161.1 pm, WNCl = 178.6º.     

钨卡宾络合物的一种形成方法及其与醛、酮的反应

四氯氧化钨或六氯化钨与不含β Ｈ的Ｇｒｉｇｎａｒｄ试剂在无水四氢呋喃中反应，形成钨的卡宾铬合物，可与醛、酮反应得到烯烃，具有类似于Ｗｉｔｉｇ试剂的功能     

矿井通风系统多目标模糊优化的数学模型

按目标分层，用分层模糊优选理论对矿井通风系统设计方案进行优选，分层时允许评价因素重叠，从而便于确定目标与评价因素的权重。本研究成果已应用于中条山有色金属公司胡家峪铜矿通风系统优化研究中，同时本文的方法也可以应用于其它领域中的类似问题。     

煤和瓦斯突出与太阳黑子活动的关系

本文在对鱼田堡煤矿和白皎煤矿历年突出资料进行统计和处理的基础上，研究了煤和瓦斯突出与太阳黑子活动的关系。发现煤和瓦斯突出年分布具有周期性，并与太阳黑子活动周期有关，讨论了太阳黑子活动影响煤和瓦斯突出的机理，最后就如何利用太阳，黑子活动周期预防煤和瓦斯突出提出了方法和建议。     

WO3 nanoflakes decorated with CuO clusters for enhanced photoelectrochemical water splitting

The low quantum efficiency arising from poor charges transfer and insufficient light absorption is one of the critical challenges toward achieving highly efficient water splitting in photoelectrochemical cells. Three dimensions(3D) structures and heterojunctions have received intensive research interests recent years due to their excellent ability to separate photo-generated charges as well as the enhanced light harvesting property. Herein,3 D Cu O/WO_3 structure was fabricated through a facile solvothermal method followed by chemical bath deposition. The loading of Cu O clusters on WO_3 nanoflake arrays results in a much improved photocurrent density compared with that of pristine WO_3 nanoflake arrays, which reaches 1.8 m A/cm2 at 1.23 V vs. the reversible hydrogen electrode. The electrochemical impedance spectroscopy measurement demonstrates that the improved performance of Cu O/WO_3 electrode is attributed to the accelerated charge transfer kinetics as a result of the desirable band alignment in Cu O/WO_3 heterojunction. This work demonstrates a facile strategy to construct superior WO_3 electrode, which will ultimately allow for efficient storage of solar energy into hydrogen.     

萍乡煤矿在中国近代工业史上的地位与作用探析

诞生于清朝末年的萍乡煤矿,是早期洋务运动的产物,是中国最早采用西方先进生产技术和管理的现代化矿井,位列中国近代工业十大厂矿之一。本文从中国民族产业发展和经济社会转型层面,全新探析了萍乡煤矿创建和发展在中国近代工业经济史上的重要历史意义,以及安源精神的最初形成与发展。     

透视煤矿住宅区规划设计中的几个问题

煤炭企业为国民经济做出重要的贡献,煤矿工人长年在井下辛勤地工作,支撑着煤炭企业的发展。本文通过对煤矿工人住宅区的现状透视,找出矿区规划设计存在的问题,并分析原因。本文提出职能部门应及时进行整体规划,形成齐抓共管、共建的规划体系,并针对住宅环境、商业住宅的开发、住宅设计中的人性化问题进行分析透视,构建人、环境、住宅的和谐统一。     

矿井通风系统合理性的评价

从技术方面、经济方面和安全程度方面分析了矿井通风系统合理性的影响因素,包括：结构合理性、用风地点角联数、风速超限状况、风机运转稳定性、矿井风压、风量供需比、设备购置费、巷道维护费、吨煤通风电费、矿山抗灾能力。选择层次分析法构建了矿井通风系统合理性评价模型,确定了各评价指标的权重并进行排序,得出了相关结论,即结构合理性、用风地点角联数、风速超限状况及风机运转稳定性对矿井通风系统合理性具有重要影响。     

WO3/CeO2对溴酚蓝的光催化降解性能

用复相光催化剂WO3/CeO2对含溴酚蓝的水溶液处理进行了研究.探讨了光催化剂作用机理,讨论了光催化剂的配比、溴酚蓝的起始浓度、光催化剂的用量、试液的pH 值、双氧水的用量、光照时间与溴酚蓝溶液脱色率的关系.实验结果表明:催化剂配比WO3:CeO2=3:1,试液溴酚蓝起始浓度为10 mg/L,催化剂用量为0.400 g ,pH =6.3,双氧水的用量为0.20 mL,光照6 h,溴酚蓝溶液的脱色率可以达到95.5%.