Structural Elucidation of {[(CH3)2SnCl2·H2O]2·18-crown-6} n and its Hydrogen Bonding in Solution by HMBC Spectroscopy

Behavior of {[(CH₃)₂SnCl₂·H₂O]₂·18-crown-6}_n in solution have been investigated by HMBC NMR. The results show that coordination of water to tin containing species and its hydrogen bonding to crown ether remains intact in non-coordinating solvent in contrast to coordinating solvent. H-NMR reveals that the chemical shift of water in complex varies by solvent of crystallization.     

Voltammetric Behavior of Arsenic(III) in the Presence of Sodium Diethyl Dithiocarbamate and Its Determination in Water and Highly Saline Samples by Adsorptive Stripping Voltammetry

This paper describes the voltammetric behavior of As(III) at the hanging mercury drop electrode (HMDE) in the presence of sodium diethyl dithiocarbamate (SDDC) and a new voltammetric method for the determination of As(III) at trace levels. The method is based on the adsorptive deposition of a As(III) complex with SDDC at ?0.45 V (vs. Ag/AgCl) on the HMDE in acidic medium of 0.01 mol L^?1 HCl (pH 2.0) and its cathodic stripping during the potential scan (100 mV s^?1). The linear range for the determination of As(III) in the presence of SDDC (4 μmol L^?1) in water samples was between 1 and 10 μg L^?1 for a deposition time of 300 s (r=0.994) and between 10 and 100 μg L^?1 for a deposition time of 60 s (r=0.999). For the determination of As(III) in dialysis concentrate samples, the linear range was between 5 and 25 μg L^?1 for a deposition time of 180 s (r=0.992) and between 10 and 100 μg L^?1 for a deposition time of 60 s (r=0.996). Detection limits of 0.3 and 2.2 μg L^?1 in water and dialysis concentrate samples were calculated for the method using a deposition time of 300 and 180 s, respectively. Recovery values between 93.0 and 110.0% for As(III) added to deionized, mineral, seawater (synthetic and real) and dialysis concentrate samples prove the satisfactory accuracy and applicability of the procedure.     

含芳硫基的新三唑类化合物的合成及生物活性研究

许多三唑类化合物具有优良的杀菌和植物生长调节活性 ,如三唑酮、三唑醇、烯效唑、烯唑醇等 ,对常见真菌病害具有很好的防治效果 ,并具有增产、抗倒和生长调节作用 ,已成为重要的杀菌剂类型 [1] .为筛选新型高活性三唑类杀菌剂和探讨其活性与结构间的关系 ,我们利用生物等排体理论以常规三唑类杀菌剂三唑酮为先导物设计合成了 1 6个含芳硫基的新三唑类化合物 ,其合成路线如下 :RCCH2 BrO+HNNNB NRCCH2O NNHAC-Na ACBr2NRCCHOBrNN(1 ) (2 ) (3 )3 +SH 　R′B NRCCHOS　R′NN　 (4 )RCCH2 CH2 NMe2 .HClO+HNNNH2 O…     

粗糙化银电极上氰基钴胺素的电化学行为

比较研究氰基钴胺素在光滑和粗糙化银电极上的电化学行为，发现在光滑银电极上氰基钴胺素的还原为一个二电子过程，而在粗糙化银电极上则为两个一电子过程，其原因是由于粗糙化银电极对氰根的强吸附作用。     

2-(10-Diazo-10H-anthracen-9-ylidene)-malonodinitrile: A convenient precursor of 9,10-disubstituted anthracenes

Summary The acid promoted decomposition of 2-(10-diazo-10H-anthracen-9-ylidene)-malonodinitrile in the presence of water, methanol, ethanol, acetic and propionic acid, ethyl thioglycolate,p-thiocresole, and acetyl acetone yielding 9,10-disubstituted 9,10-dihydroanthracenes was investigated. Treatment of the reaction products with tri-ethyl amine followed by hydrochloric acid caused their tautomerization to the corresponding 9,10-disubstituted anthracenes. A mechanism for this reaction is proposed. The first example of an intermolecular C-C-bond formation during the protic acid promoted decomposition of a diazo compound in the presence of CH-acids was found. An improved procedure for the preparation of the starting diazo compound, which may serve as a convenient precursor of 9,10-disubstituted anthracenes, is described.Cordially dedicated to Prof. Dr.K. Winsauer on the occasion of his 70^th birthday     

微量热法研究γ-Mo2N催化剂表面氢的微分吸附热

Differential heats of H 2 adsorption on γ-Mo2N catalysts were studied by using microcalorimetry. Samples with high and medium surface areas (90 and 17 m2•g -1 ) present a homogeneous energetic distribution of surface sites, which corresponds with the preferential orientation of their (200) planes. Molybdenum nitride with low surface area (8 m2•g -1 ) displays a heterogeneous energetic distribution of H 2 adsorption sites. The higher initial differential heat of hydrogen adsorption observed for the low surface Mo nitride was attributed to species adsorbed on surface sites associated with the (111) plane.     

Anab initio investigation of Cu2Se and Cu4Se2

Summary Experimentally known copper selenium clusters show extraordinary geometrical features, especially short Cu-Cu distances. We report the first theoretical investigation of Cu₂Se and Cu₄Se₂. Various quantum chemical methods (SCF, MP2, CPF, CCSD, CCSD(T), LDF) are applied to determine the importance of dynamic electron correlation. We find that inclusion of correlation does not essentially change the electronic structure of the clusters but has a strong influence on geometries. To reduce the computational effort we apply effective core potentials (ECPs) in combination with small, but carefully optimized basis sets. The applicability of simple modellings of correlation energies for approximate inclusion of correlation effects in SCF geometry optimizations is tested.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. 59. Cyclopentadienyl-2-(dimethylaminomethyl)ferrocenyl-Verbindungen elektronenarmer 3 d-Elemente

Contributions to the Chemistry of Transition Metal Alkyl Compounds. 59. Cyclopentadienyl-2-(dimethylaminomethyl)ferrocenyl Compounds of Early 3 d-Elements Compounds of the type (C₅H₅)₂M(FcN) (M = Sc ( 1 ), Ti ( 2 ), V ( 3 ), Cr ( 4 ); FcN = 2-dimethylaminomethyl)ferrocenyl group), and (C₅H₅)M(FcN)₂ (M = Ti ( 5 ), Cr ( 6 ) were synthesized and investigated. A detailled characterization with respect to the existence of chelate structures was realized by the uv-vis, ¹H-n.m.r. spectroscopic measurements and determination of magnetic moments.     

1,2-聚丁二烯介电松弛的复平面分析

本文对1,2-聚丁二烯的介电松弛进行了复平面分析.结果表明,在1,2-聚丁二烯的玻璃化转变过程中,ε″(ω)与ε＇(ω)的关系满足Havriliak-Negami方程.由复平面图求出了样品的静态和光频下的介电系数,平均松弛时间和松弛时间分布参数.利用所得数据讨论了1,2-聚丁二烯在玻璃化转变过程中的构象变化、松弛时间分布和平均偶极矩等问题.     

Excess thermodynamic properties of the 2-propanol + dichloromethane system at 25°C

Densities, viscosities, enthalpies, vapor-liquid equilibria, and surface tensions were determined at 25°C for the 2-propanol+dichloromethane system. From the experimental results excess volumes, viscosities, enthalpies, Gibbs energies, and excess surface tensions were calculated. An attempt has been made to explain the observed deviations from ideal behavior on the basis of intermolecular interactions.