Reaction of Molybdenum Hexa-carbonyl with Mercapto-pyridine （PySH） or Mercapto-pyridine Oxide （PyS→O） and Crystal Structure of [Et4N][Mo2（PyS）3（CO）5]

Introduction Mercapto-pyridine, C5H4NS-(PyS), containing two active atoms, S and N, is a bidentate ligand, which may act as a 3-electron donor or a 5-electron donor and may be a bridging ligand to link two metal atoms to form polynuclear metal clusters or a chelating agent to coor-dinate to a metal atom by S and N atoms. So the mer-capto-pyridine is a very important reagent and its reac-tion with metal compound is very useful for simulating the active center in metal enzymes and syntheses …     

用UBI-QEP方法分析钴系Fischer-Tropsch合成催化反应机理

采用unity bond index-quadratic exponential potential(UBI-QEP)方法, 以Co(0001) 单晶为模型催化剂, 对Fischer-Tropsch(F-T)合成的三种可能反应机理(表面碳化物机理、烯醇机理和CO插入机理)进行了全面的能学分析. 计算结果表明, 通过表面碳化物机理生成烃类产物从能学角度看较为合理, 其中CO_ads表面解离和C_ads加氢具有较高的活化能垒, 可能是整个F-T反应序列中的慢步骤; 通过CH_2,ads插入金属-烷基键实现链增长的活化能垒最低, 是能量上有利的链增长方式; 在Co(0001)晶面上烷基经β-H消除生成烯烃的活化能垒低于加氢生成烷烃, 而通过CO插入机理生成的有机含氧化合物的二次反应能垒较低, 从而导致其在Co催化剂上的低选择性. 此外, 与Fe/W(110)相比, Co金属上的CH_x,ads加氢以及CH_2,ads插入的活化能垒较低, 从而解释了Co催化剂上甲烷选择性较高和倾向于生成重质烃类产物的特性.     

HF在α-AlF3(0001)表面吸附的密度泛函理论研究

利用密度泛函理论系统研究了不同覆盖度下HF在3F、2F、1F与Al 终端的α-AlF₃(0001)表面的吸附行为, 分析了HF与不同终端表面相互作用的电子机制. 计算结果表明: HF在3F终端的α-AlF₃(0001)表面物理吸附; 在2F及1F终端表面化学吸附, 形成Al-F键和FHF结构, 使HF分子活化, 可以参加下一步的氟化反应; 在Al 终端表面解离吸附形成Al-F与Al-H键. 3F、2F、1F及Al 终端表面配位不饱和数目分别为0、1、2与3配位.不同覆盖度研究表明, 在2F终端表面上, 吸附一个HF分子使表面Al 配位达到饱和, 后续吸附的HF为物理吸附; 而在1F与Al 终端表面仍可化学吸附. 因此, 推测α-AlF₃暴露不同终端表面中Al 原子配位不饱和数越高, 其对HF吸附与活化能力越强, 可能的氟化催化反应活性越高. 差分电荷密度与电子态密度分析表明, HF与3F终端α-AlF₃(0001)表面发生弱相互作用, 而与2F、1F与Al 终端表面形成较强的电子相互作用.     

Application of carbon-based nanomaterials in sample preparation: A review

In this paper, a broad overview on the applications of different carbon-based nanomaterials, including nanodiamonds, fullerenes, carbon nanotubes, graphene, carbon nanofibers, carbon nanocones-disks and nanohorns, as well as their functionalized forms, in sample preparation is provided. Particular attention has been paid to graphene because many papers regarding its application in this research field are becoming available. The distinctive properties, derivatization methods and application techniques of these materials were summarized and compared. According to their research status and perspective, these nanomaterials were classified in four groups (I: graphene and carbon nanotubes; II: carbon nanofibers; III: fullerenes; and IV: nanodiamonds, carbon nanocones/disks and carbon nanohorns) and characteristics and future trends of every group were discussed.     

中药金礞石红外指纹图谱相似度分析

分析金礞石红外指纹图谱的相似度,建立金礞石药材质量的红外指纹图谱评价方法.用傅里叶变换红外光谱仪测定金礞石药材样品的红外光谱,以共有模式建立金礞石的对照红外指纹图谱,采用相关系数法和夹角余弦法计算药材样品红外指纹图谱与对照指纹图谱的相似度.19件样品中,符合《中国药典》规定者红外指纹图谱与对照指纹图谱的相似度(相关系数...     

Hydrogen fluoride adsorption and reaction on the α-Al2O3(0001) surface: a density functional theory study

The adsorption and reaction behaviors of HF on the α-Al(2)O(3)(0001) surface are systematically investigated using density functional theory method. By increasing the number of HF molecules in a p(2 × 1) α-Al(2)O(3)(0001) slab, we find that HF is chemically dissociated at low coverage; while both physical and dissociative adsorption occurs at a 3/2 monolayer (ML) coverage. At the same coverage (1.0 ML), diverse configurations of the dissociated HF are obtained in the p(2 × 1) model; while only one is observed in the p(1 × 1) slab due to its smaller surface area compared with the former one. Preliminary fluorination reaction study suggests that the total energy of two dissociated HF in the p(2 × 1) slab increases by 1.00 and 0.72 eV for the formation and desorption of water intermediate, respectively. The coadsorption behaviors of HF and H(2)O indicate that the pre-adsorbed water is unfavorable for the fluorination of Al(2)O(3), which is well consistent with the experimental results. The calculated density of states show that the peak of σ(H-F) disappears, while the peaks of σ(H-O) and σ(Al-F) are observed at -8.4 and -5 to -3 eV for the dissociated HF. Charge density difference analysis indicates that the dissociated F atom attracts electrons, while no obvious changes on electrons are observed for the surface Al atoms.     

Synthesis, Structure, Characterization and Electrochemistry of a New Dinuclear W(0)-complex [Et4N]2[W2(CO)8(SCH2COOMe)2]

Reaction of Et4NCl, NaSCH2COOMe and W(CO)6 in MeCN affords a new dinuclear tungsten(0) complex [Et4N]2[W2(CO)8(SCH2COOMe)2] (1). The crystal and molecular structure has been determined by X-ray single crystal diffraction. 1 Crystallized in the triclinic, space group P with a=11.141(7), b=10.267(4), c=10.798(3)(); α=93.96(3), β=96.88(4), γ=114.97(5)°; V=1003()3, Z=1, Dc=1.76 g/cm3, μ=60.1 cm-1, R=0.042 and Rw=0.050 for 2967 independent reflections with I>3.0 σ(I). 1 contains a WS2W planar core with nonbonding W...W distance of 3.9611(5)(), and its IR, 13C NMR, and cyclic voltammetry were measured and discussed.     

Synthesis and Crystal Structure of Pyridine－2－thiolato－Molybdenum Complex［Et_4N］［Mo（CO_4）（pyS）］

ＳｙｎｔｈｅｓｉｓａｎｄＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆＰｙｒｉｄｉｎｅ－２－ｔｈｉｏｌａｔｏ－ＭｏｌｙｂｄｅｎｕｍＣｏｍｐｌｅｘ［Ｅｔ_４Ｎ］［Ｍｏ（ＣＯ_４）（ｐｙＳ）］ＹｕＰｅｉ－Ｈｕａ；ＨｕａｎｇＬｉａｎｇ－Ｒｅｎ；ＺｈｕａｎｇＢｏ－Ｔａｏ...     

Reaction of Mo(CO)6 with Alkoxide: Synthesis and Structure of the Mo(0)-OR Complex [Et4N]3[Mo2(CO)6(μ-OC6H4OCH2C6H5)3]

The reaction of molybdenum hexacarbonyl with C6H5CH2OC6H4ONa and Et4NBr in CH3CN at 60 ℃ afforded the di-nuclear Mo(0) compound [Et4N]3[Mo2(CO)6(μ-OC6H4OCH2- C6H5)3] 1. 1 crystallizes in monoclinic, space group P21/c with a=15.359(2), b=18.378(3), c=24.952(2)(A), β=102.268(4)°, V=6882.3(16) (A)3, Mr=1348.34, Z=4, Dc=1.301 g/cm3, F(000)=2832 and μ= 0.424 mm-1. The final R=0.0606 and wR=0.1552 for 9396 observed reflections (Ⅰ ＞ 2σ(Ⅰ)). 1 contains a [Mo2O3]3- core in triangular bi-pyramidal configuration and each Mo atom adopts a distorted octahedral geometry with three carbon atoms from carbonyls and three μ-O atoms from C6H5CH2OC6H4O- bridging ligands. The Mo…Mo distance is 3.30(8) (A), indicating no metalmetal bonding. A formation pathway via forming a di-molybdenum(0) di-bridging OR compound [Mo2(μ-OR)2(CO)8]2- has been figured out and the reaction of Mo(CO)6 with alkoxide has also been discussed.     

若干含硫双核低价态钼—羰基簇合物的IR和共振Raman光谱研究

研究了簇合物[Et4N]2[Mo2（CO)8（μ-SPh）2]（1）、MO2（CO）8（μ-SPh）2（2）、MO2－（CO）6（μ-SPh）2（CH3CN）2（3）、Mo2（CO）6（μ-SPh）2（PPh3）2（4）的红外和共振Raman光谱。分别对它们的特征振动频率进行了归属。研究了Mo2（CO）6（μ-SPh）2L2中L的σ给体强度和π受体强度对影响的协同效应。结果表明，在3中CH3CN的π受体强度和4中PPh3的σ给体强度对的影响起主导作用。在2、3、4中L的σ效应对的影响起主导作用。