Relaxational behavior of birefringence of aqueous carboxymethylcellulose under an alternating electric field at frequencies ranging from 0.1 Hz to 100 kHz

The d. c. component of birefringence of aqueous carboxymethylcellulose (CMC) under an a. c. electric field was measured at frequencies ranging from 0.1 Hz to 100 kHz. Three samples of different molecular weights were studied with varying degree of neutralization, polymer concentration and added salt concentration. The dispersion curve of birefringence consists of three relaxation bands,A, B andC in order of decreasing frequency. RelaxationB with a negative relaxation strength is ascribed to end-over-end rotation of almost rodlike CMC molecules. RelaxationA with a positive strength is attributed to the relaxation of electrical polarizability along the minor axis of molecule. RelaxationC possesses also a positive strength and is induced by clusters of CMC molecules.Dedicated to Prof. Dr. F. H. Müller.     

Synthesis and structural studies of polynuclear ruthenium clusters derived from reactions of 1,2,3,4-tetraphenyl-1,2,3,4-tetraphospholane with [Ru3(CO)12]

Reactions of 1,2,3,4-tetraphenyl-1,2,3,4-tetraphospholane (I) with triruthenium dodecacarbonyl at different temperatures result in the cleavage of P-P bonds and even P-C bond(s) in I to afford a series of new ruthenium cluster derivatives containing phosphido and phosphinidene ligands: a penta-ruthenium wing-tip bridged butterfly cluster [Ru₅(CO)₁₁(μ₄-PPh)(μ₃-PPh){(μ₄-η²-(PPh)₂CH₂}] (1), a hepta-ruthenium polyhedral (consisting of two fused square pyramids with a co-apex) cluster [Ru₇(CO)₁₅(μ₄-PPh)₂{(μ₂-PPh)₂CH₂}](2), a linked penta-ruthenium cluster [Ru₄(CO)₁₀(μ₄-PPh)(μ₃-PPh)₂(μ₃-η²-PPhCH₂)Ru(CO)₃] (3), and a hepta-nuclear polyhedral (consisting of two fused square pyramids with different apexes) cluster [Ru₇(CO)₁₅(μ₄-PPh)₂{(μ₂-PPh)₂CH₂}](4). Clusters 2 and 4 are isomeric and differ only in the connection of the two square pyramids in the Ru₇ polyhedron. All the newly obtained clusters have been fully characterized by spectroscopic (IR, FABMS, ¹H- and ³¹P-NMR spectroscopy) and analytical techniques, and their molecular structures are established by single crystal X-ray diffraction analysis.     

Transition metal 1,2-bidentate thiolates as building blocks and their construction into cluster complexes

Simple fragments of transition metal 1,2-bidentate thiolates, the so-called building blocks of the general compositions ML₃, ML₂, ML, M(O)L₂, ML₂L, MLL, etc. have been proposed to constitute the di-, tri- and tetranuclear complexes concerned in this review. Structureal regularities and characteristics have been discussed and summarized according to the thiolato ligands edt and pdt, bdt and tdt, mp, and mpo, and mpp, respectively.Abbreviations H₂mpo o-mercaptophenol - Hmpo 2-mercaptopyridine-N-oxide - R₂dtc N,N-dialkyldithiocarbamate - Haet 2-aminoethanethiol - H₂bdt o-benzenedithiol - H₂pdt 1,2-propanedithiol - H₂tdt toluene-3,4-dithiol - Hmpp-mppH bis-(3-hydroxy-2-pyridyl)disulfide - Hmp-mpH bis-(2-oxyphenyl)disulfide - H₂edt 1,2-ethanedithiol - dppe 1,2-bis(diphenylphosphino)ethane - H₂tedt 3,4,5,6-tetrachlorobenzene-1,2-dithiol - H₂tpdt 3-thiapentane-1,5-dithiol - H₂mnt maleonitriledithiol - Him imidazole - Bz benzyl - py pyridine     

~3Δ、~3Π、~3Σ~＋Ni—CO分子簇的从头算研究

用从头算研究了ｄ空穴位置不同对Ｎｉ—ＣＯ成键机制的影响。结果表明，Ｎｉ—ＣＯ键中σ／π接受作用的相对强弱，取决于Ｎｉ—ＣＯ簇所处的能态。σ空间电子云较π空间电子云弥散，因而Ｎｉ—ＣＯ簇的稳定性与σ空间电子云的排斥密切相关。随着Ｎｉ４ｐσ轨道上电子占据数的增加，Ｎｉ—ＣＯ稳定性减弱。比较了分子簇Ｎｉ—ＣＯ与ＮｉＣＯ分子及ＣＯ／Ｎｉ化学吸附体系之间的性质。     

高效液相色谱直接分离μ-FcCCHCoW(CO)5(CpCOOC2H5)簇合物对映体

将三（苯基氨基甲酸）支链淀粉酯涂敷在硅胶上制成了手性固定相．将支链淀粉与过量的苯异氰酸酯在吡啶中反应得到的苯基氨基甲酸酯溶解并涂敷在用３－氨基丙基三乙氧基硅烷处理过的硅胶上，涂敷量为０．４５／２．５５（重量比）．用此手性固定相拆分了外消旋的簇合物μ－ＦｃＣＣＨＣｏＷ（ＣＯ）５（ＣｐＣＯＯＣ２Ｈ５）．拆分在室温下进行，洗脱液为甲醇，流速为０．５ｍＬ／ｍｉｎ．     

原子簇P12（D3d）的理论研究

利用Ｇａｕｓｓｉａｎ－９２程序在６－３１Ｇ基组下优化Ｐ１２（Ｄ３ｄ）构型，研究了３Ｐ４（Ｔｄ）→Ｐ１２（Ｄ３ｄ）的相对能量，计算结果为△Ｅ＝Ｅｐ１２（Ｄ３ｄ）－３Ｅｐ４（Ｔｄ）＝－７９．８４４ｋＪ／ｍｏｌ，优化Ｐ１２（Ｄ３ｄ）获得的Ｐ－Ｐ键键长接近于实验测得的Ｐ－Ｐ单键键长，并进一步在该基组下计算了Ｐ１２（Ｄ３ｄ）原子簇的振动频率，得到的全部为正频率，表明原子簇Ｐ１２的Ｄ３ｄ构型是位能面上的稳定点     

HYDROFORMYLATION CATALYSIS USING POLYMER-SUPPORTED MULTINUCLEAR RHODIUM CARBONYL CLUSTER CATALYSTS

A series of polymer-supported tetranuclear rhodium carbonyl cluster catalysts were prepared b the reaction of Rh_4(CO)_(12) with several kinds of polymer supports such as crosslinked poly (N-vinylpyrrolidone) (PNVP) and crosslinked poly ( styrene-co-maleic anhydride) (PMAn), and subsequently were used to catalyze the hydroformylation of olefins. The catalysts were characterized by IR, SEM and XPS. The influence of the supports structure and crosslinking, metal's content and particle size of the supports on the catalysts hydroformylation properties was studied. The factors which affect the catalytic conversion were also examined. The experimental results show that the polymer-supported Rh cluster catalysts possess very high catalytic activity and aldehyde selectivity as well as good reproducibility.     

Application of an Ion Beam Technique for the Design of Visible Light-Sensitive, Highly Efficient and Highly Selective Photocatalysts: Ion-Implantation and Ionized Cluster Beam Methods

As a new concept for the design of effective photocatalysts, an ion beam technology using accelerated metal ions, a metal ion implantation and an ionized cluster beam (ICB) method, have been applied to design unique photocatalysts. The metal ion implantation of TiO₂ and Ti-containing zeolites with highly accelerated metal ions (V⁺, Cr⁺, etc.) is useful in designing photocatalysts that can operate efficiently under visible light irradiation. Also, an ICB method with a low acceleration energy is useful in preparing transparent TiO₂ thin films on various types of substrates for the efficient photocatalytic degradation of pollutants diluted in water and air. The combination of the ICB method and metal ion implantation can develop the TiO₂ thin films that are able to operate not only under UV light but also under visible light irradiation.     

王冠高聚物担载四核钴羰基簇催化剂的醛化反应活性

本文用二苯并-18-冠-6高聚物作因相化载体,通过化学健合,合成了担载的四核钴羰基簇催化剂Crown-Co_4。,并对该催化剂进行了元素分析、红外光谱及X射线光电子能谱(XPS)等方面的测试分析;还考察了不同温度、不同极性溶剂及不同类型烯烃对醛化活性的影响。实验证明,该催化剂对直链端位烯烃的醛化活性高于均相的苯基-四核钴羰基簇催化利Ph-Co_4。。二苯并-18-冠-6高聚物载体能明显改善催化性能。     

Reduced Overlap Population Analysis for Triosmium Clusters

The use of reduced overlap population (ROP) analysis from EHMO calculations as a means to gauge the presence of metal–metal bonds in triosmium clusters is examined. A number of triosmium clusters containing bridging ligands have been used as test cases, including the bis-ethoxy bridged cluster Os₃(μ-OEt)₂(CO)₁₀, 1b, and some of its group 15 derivatives Os₃(μ-OEt)₂(CO)₉(EPh₃), 2. These latter clusters are newly synthesized and have been characterized completely, including by single-crystal X-ray crystallographic studies. In honour of Professor Dieter Fenske on his 65th birthday.