ZrIV‐ und TaV‐Komplexe mit methanoverbrückten Bis(aryloxy)‐Liganden

Zr^IV and Ta^V Complexes with Methano‐Bridged Bis(aryloxy) Ligands The bis(aryloxy) ligand precursor compounds bis(2‐trimethylsiloxy‐5‐tbutylphenyl)methane (L–SiMe₃) and its bromoderivative (2‐trimethylsiloxy‐3‐bromo‐5‐tbutylphenyl)(2′‐trimethylsiloxy‐5′‐tbutylphenyl)methane (L^Br–SiMe₃) are prepared in analogy to the corresponding calixarenes in excellent yields. X‐ray structure analysis for L^Br–SiMe₃: space group P2₁/c, a = 12.462(7), b = 10.466(6), c = 23.315(14) Å, β = 105.02(4)°, V = 2937(3) ų, Z = 4. L–SiMe₃ and L^Br–SiMe₃ react with Zr^IV and Ta^V chlorides in very good yields forming di‐ and trinuclear complexes. From the reaction of CpZrCl₃ with L^Br–SiMe₃ in the ratio of 3 : 2 a Zr₃ complex ( 7 ) is obtained, with one L^Br ligand only, which Zr atoms are bridged by a μ₃‐oxygen. The X‐ray structure analysis of 7 (space group R 3, a = 33.23(6), c = 24.47(8) Å, V = 23405(128) ų, Z = 18) additionally reveals that one phenolato oxygen atom of the L^Br ligand is terminally bound to a distorted tetragonal‐pyramidal coordinated Zr atom, while the second phenolato oxygen atom of the L^Br ligand forms a bridge to another Zr atom with a distorted octahedral coordination. The third Zr atom is also found in a distorted octahedral coordination mode. The reactions of L–SiMe₃ and L^Br–SiMe₃ with CpTaCl₄ and TaCl₅ yield dinuclear Ta complexes with a bridging bis(aryloxy) ligand. NMR spectroscopic data point out that the coordination of the bis(aryloxy) ligands in the Ta complexes very much resembles that in the Zr₃‐complex with one terminal and one bridging phenolato oxygen atom. The Zr₃ and the Ta complexes L^BrTa₂Cp₂Cl₆ and LTa₂Cl₈ were tested with respect to their catalytic properties in olefin polymerisation reactions in the presence of MAO.     

B(C6F5)3在有机化学及高分子化学中的应用研究进展

B(C6F5)3与传统的Lewis酸相比,具有化学性质稳定、酸性强、使用方便等优点,被称为非传统的Lewis酸。B(C6F5)3的应用领域已经从最初的烯烃聚合共催化剂向有机化学及高分子化学的其它各个领域发展。B(C6F5)3催化的反应与传统Lewis酸催化的反应在反应机理及反应结果上均有很大的不同。本文主要综述B(C6F5)3近年来在有机化学及高分子化学中的应用研究成果。     

Enantioselective hydrogenation of olefins with axial chiral iridium QUINAP complex

(S)-QUINAP reacted with [Ir(cod)Cl]₂ to form a new chelating iridium complex in 77.4% yield. The iridium complex was proved to be a highly efficient catalyst for the enantioselective hydrogenation of olefins. 33.4-95.1% ee were obtained for the hydrogenation of unfunctionalized olefins and 90.8-96.1% ee were obtained for functionalized olefins.     

Fluorinated bis(phenoxy-imine) Ti complexes with MAO: Remarkable catalysts for living ethylene and syndioselective living propylene polymerization

Based on new results as well as the reported data, the ethylene and propylene polymerization behavior of bis(phenoxy-imine) Ti complexes (Ti-FI Catalysts) combined with MAO (particularly that of their fluorinated versions) is discussed, with an emphasis on the characteristics and mechanisms of living ethylene and syndioselective living propylene polymerization. Unlike common living olefin polymerization catalysts, fluorinated Ti-FI Catalysts with MAO display thermally robust living behavior and polymerize ethylene in a highly controlled manner at temperatures as high as 50 °C. Additionally, despite being C₂-symmetric catalysts, fluorinated Ti-FI Catalysts/MAO mediate highly syndioselective living propylene polymerization. Fluorinated Ti-FI Catalysts that we developed are the first examples of catalysts that induce the living polymerization of both ethylene and propylene. In addition, they are also the first examples of living and, at the same time, highly stereoselective propylene polymerization catalysts. The versatile and robust living nature of the fluorinated Ti-FI Catalysts allows the preparation of a wide variety of unique living polymers; some of which can even be produced catalytically. On the basis of theoretical calculations as well as experimental results, we conclude that these unusual polymerization features of fluorinated Ti-FI Catalysts originate from an attractive interaction between the ligand and a growing polymer chain and/or the fluxional character of the catalyst coupled with 2,1-regiochemistry. This is in stark contrast to group 4 metallocene catalysts, which control olefin polymerization mainly by repulsive interactions based on the rigidly organized ligand frameworks.     

Microwave-accelerated cross-metathesis reactions of N-allyl amino acid substrates

Microwave heating has been utilised for the cross-metathesis reaction of N-allyl amino acid substrates to generate olefin homodimers. Remarkable acceleration of the cross-metathesis reaction (minutes compared to hours) over conventional reflux heating was observed. In addition, improved reaction yields and similar E/Z ratios for the cross-metathesis products were achieved.     

银改性硅藻土材料捕集烯烃的研究

银改性硅藻土作为烯烃捕集材料已用于多维气相色谱分析汽油组分，烯烃捕集容量与硅藻土的比表面积和AgNO3负载量有关。采用X射线衍射(XRD)测定不同载银量的材料中晶相AgNO3的衍射强度，得到AgNO3在硅藻土表面单分子层最大分散量。实验结果与密置单层模型计算的AgNO3最大分散量接近，与色谱法测定结果相吻合。热分析结果表明：捕集材料在使用过程中具有良好的稳定性；吸附的烯烃可以定量回收。     

多核钴铁羰基簇结构与催化性能研究

本文以ＣｌＣＣｏ_３（ＣＯ）_９，Ｅｔ_４Ｎ［ＦｅＣｏ_３（ＣＯ）_（１２）］，Ｍｅ_４Ｎ［Ｆｅ_６Ｃ（ＣＯ）_（１６）］诸羰基簇为研究对象，采用激光等离子体源飞行时间质谱及量化计算相结合，对上述羰基簇合物结构及稳定性进行了研究，并将所得结果用于推论ＣｌＣＣｏ_３（ＣＯ）_９及Ｅｔ_４Ｎ［ＦｅＣｏ_３（ＣＯ）_（１２）］的烯烃氢甲酰化反应活性中间体和α－Ａｌ_２Ｏ_３担载的相应簇合物的ＣＯ加氢活性物种。     

Ozonolysis of olefins VIII. Synthesis of phenoxyacetaldehydes by ozonolysis of allylphenylethers

Summary A new route for the preparation of a series of phenoxyacetaldehydes (2a–j) which are useful intermediates or products, is described. It starts from the easily available allylphenylethers1a–j which are ozonized at –40 °C and further treated with dimethylsulfide to give solutions of the corresponding phenoxyacetaldehydes2a–j; these are purified by column chromatography. Reaction of2a–j with 1-methyl-1-phenylhydrazine leads to the corresponding hydrazones3a–c,3e–g,3i, and3j. The aldehydes can also be transformed into the stable dimethylcetals4a,4e,4h, and4i by reaction with trimethyl orthoformate.

---

Ozonolyse von Olefinen, 8. Mitt. Synthese von Phenoxyacetaldehyden durch Ozonolyse von Allylphenylethern

Zusammenfassung Ein neuer Weg, die als Synthone nützlichen Phenoxyacetaldehyde2a–j darzustellen, wird beschrieben. Dazu werden die leicht zugänglichen Allylphenylether1a–j bei –40 °C ozonisiert und anschließend mit Dimethylsulfid reduziert, um Lösungen von2a–j zu erhalten. Reaktion von2a–j mit 1-Methyl-1-phenylhydrazin führt zu den entsprechenden N-Methyl-N-phenylhydrazonen3a–c,3e–g,ei und3j. Die Aldehyde können auch durch Reaktion mit Trimethylorthoformiat in die stabileren Dimethylacetale4a,4e,4h und4i übergeführt werden.

     

新型烯烃聚合催化剂研究进展

由于过渡金属催化剂在烯烃聚合方面具有高活性和良好的分子剪裁性,通过调节催化剂的微结构或温度、压力等聚合环境的变化,可以在分子层次上实现烯烃聚合物的分子设计与组装,实现聚合物物理性质的调控,最近引起了人们的广泛关注。本文介绍了过渡金属催化剂的合成及其负载化,水相烯烃聚合及活性聚合等方面的研究进展。     

The synthesis and X-ray structure of trans-NiCl2(1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene)2; attempts to polymerize olefins utilizing a nickel(II) complex of a sterically demanding N-heterocyclic carbene

The compound trans-NiCl₂(IPr)₂ (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) is synthesized and characterized crystallographically. In combination with MAO, it is converted to an intermediate which catalyses the dimerization of ethylene but which not the polymerization of ethylene, propylene or 1-hexene.