共查询到20条相似文献,搜索用时 133 毫秒
1.
稀土金属有机化合物的合成和研究已经取得了很大进展,特别是一系列σ键化合物的合成开辟了金属有机化学的新领域。对稀土金属有机化合物的研究既具有重要的理论意义,也有很大的实际意义。稀土金属有机化合物的发展基于二茂铁[Fe(C_5H_5)_2]的合成。三十年代后期的PIetz和四十年代中期的Gilman和Jones,他们就试图合成ⅢB族元素金属有机化合物,结果没有成功。五十年代中期的Wilkinson和Birmingham首先合成了稀土金属三环戊二烯化合物。到六十年代已能合成出一系列稀土金属环戊二烯化合物。稀土金属有机化合物在八十年代的今天仍是一个非常活跃的学科领域。稀土金属有机化合物可按其相连基团(或配位基)的类型来分类;也可以按稀土金属与配位体之间键的类型来分 相似文献
2.
3.
4.
综述了中国稀土金属有机化学的进展。包括三环戊二烯基稀土配合物,环戊二烯基稀土氯化物,含有稀土碳σ键配合物,稀土有机氢化物,烯丙基稀土配合物,环辛四烯基稀土衍生物,中性芳烃稀土配合物,二价稀土配合物及含过渡金属,稀土异核配合物的合成和结构以及稀土有机化合物催化烯烃氢化、异构化、聚合和在脱卤、脱氧、脱硫等反应中的应用。 相似文献
5.
6.
廉价过渡金属催化烯烃异构反应研究进展 总被引:2,自引:0,他引:2
过渡金属催化的烯烃异构反应在有机化合物合成、日用化学品合成、原料油应用和天然产物合成中都有着举足轻重的作用。廉价过渡金属由于其在资源、价格、后处理等方面的优势,日益受到研究者的重视。本文主要综述了近几十年来廉价过渡金属铁、钴、镍在催化烯烃异构反应方面的研究进展,详细阐述了不同的催化体系在催化活性、反应选择性、底物适用性及反应机理方面的特点。虽然目前的催化体系已经表现出优异的性能与应用价值,但在烯烃异构的立体选择性、区域选择性机制等方面,仍然需要更深入的研究。 相似文献
7.
近年来,利用稀土金属作为路易斯酸,与主族路易斯碱组合的路易斯酸碱对得到了开发.这类酸碱对组合通过路易斯酸与路易斯碱协同作用,从而实现底物的活化,展示了与传统稀土金属配合物不同的活化模式.其可以与氢气反应,断裂非极性的氢-氢键;也能够与羰基类、重氮类及叠氮类等不饱和小分子反应,得到一系列结构独特的稀土金属配合物.同时这类路易斯酸碱对也可以用于催化极性烯烃聚合反应、二氧化碳硅氢化还原反应中,展现出优异的催化性能.综述了上述研究结果,并对该领域的发展趋势和前景进行了展望. 相似文献
8.
9.
一、烯烃聚合及络合催化聚合聚烯烃是石油化工的重要内容,因而其合成化学也随着我国石油化工的发展而开展了许多工作,特别是在传统的络合催化体系中加入稀土金属的研究更具有我国研究工作的特色,阮埃乃、魏金柱、单成基、金鹰泰等着重对稀土金属钕的络合催化 相似文献
10.
催化剂在推动聚烯烃工业发展中有着举足轻重的作用,其中金属催化剂的设计与合成更是金属有机催化化学的关键.稀土金属具有独特的轨道结构、反应活性和配位准则,因此稀土金属配合物通过在金属中心周围引入空间位阻,在聚烯烃材料制备中表现出独特优势.其中配体是决定稀土金属配合物的结构、化学活性及稳定性等方面的关键因素.本综述介绍了茂基配体(烷基取代、芳基取代、茚和芴配体)和非茂基配体(大环四齿配体、三齿配体、双齿配体和单齿配体)的稀土金属配合物的发展及其在聚烯烃制备中的应用.这项工作旨在促进稀土金属催化剂在聚烯烃催化和金属有机催化领域的研究,为高端化、差异化聚烯烃聚合催化剂的制备提供新的设计思路和研究方法. 相似文献
11.
12.
13.
This lecture will focus two living polymerizations that can be carried out in water as well as in organic media. The first one is transition metal-catalyzed living radical polymerization, for which Ru(II) and other transition metals play a critical role to control the process; for aqueous systems, Ru(II) and Fe(II) half metallocene complexes are useful. The second is cationic polymerization with water-tolerant Lewis acids as catalysts, including rare earth triflates and boron trifluoride for selected monomers. Discussion will be directed to the design of initiating systems, search of versatile catalysts, and precision synthesis of new polymers. 相似文献
14.
Dr. Waldemar Fegler Dr. Ajay Venugopal Dr. Mathias Kramer Prof. Dr. Jun Okuda 《Angewandte Chemie (International ed. in English)》2015,54(6):1724-1736
Molecular hydrides of the rare‐earth metals play an important role as homogeneous catalysts and as counterparts of solid‐state interstitial hydrides. Structurally well‐characterized non‐metallocene‐type hydride complexes allow the study of elementary reactions that occur at rare‐earth‐metal centers and of catalytic reactions involving bonds between rare‐earth metals and hydrides. In addition to neutral hydrides, cationic derivatives have now become available. 相似文献
15.
Dr. Benjamin Oelkers Dr. Mikhail V. Butovskii Prof. Dr. Rhett Kempe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(43):13566-13579
Metal–metal bonding in heterobimetallic complexes is of fundamental interest due to its implications to both bonding theory and new reactivities. In this Concept, structurally authenticated molecular compounds with direct bonds between rare‐earth metals or actinoids and transition or main group metals are summarized. Special attention is given to the use of bond polarity as a tool for designing molecular intermetalloids incorporating rare‐earth atoms and transition metals. 相似文献
16.
Robert H. Grubbs 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1829-1933
Since the discovery that transition metals salts mixed with organoaluminum reagents catalyze the polymerization of ethylene to crystalline polyethylene, organo-metallic complexes and reagents have played a major role in the polymer industry [1]. Over the past 20 years a tremendous amount has been learned about the structures and mechanisms of reactions of complexes related to those proposed to be active in these systems [2]. In the related area of olefin metathesis and ring-opening metathesis polymerization (ROMP), metal carbenes and metallacycles were proposed intermediates, and over the past few years a number of complexes with these structures that will catalyze the olefin metathesis reaction have been prepared and studied [3]. In contrast to the ill-defined classical catalysts based on Ziegler-type catalysts, these are living polymerization systems. This was first observed using Tebbe-type reagents [4]. 相似文献
17.
Scott Collins 《Coordination chemistry reviews》2011,255(1-2):118-138
Applications of transition metal amidinate [RC(NR′)2], guanidinate and amidopyridine complexes to olefin coordination polymerization are reviewed. In addition, the use of complexes, featuring closely related ligands, such as phosphonamide or iminophosphonamide [R2P(NR′)2], in olefin polymerization is highlighted. Some of these complexes have also been investigated in the stereoregular polymerization of styrene and conjugated dienes, whereas more recent work has focused on controlled ring-opening polymerization of lactones and lactides. 相似文献
18.
IVB金属配合物催化烯烃聚合的研究进展 总被引:1,自引:1,他引:0
IVB金属配合物催化烯烃聚合的研究,不仅为工业界提供大量新型高效的催化剂模型,同时也为探索烯烃配位聚合机理提供了可能.更为重要的是,这些新型的配合物催化剂,可以制备具有优异性能的新型聚烯烃树脂.研究的核心仍然是新型聚烯烃催化剂,基于配合物中配位原子种类的不同,将催化剂的种类分为氮配位和氧配位催化剂.文中综述了近年来IVB金属配合物作为烯烃聚合催化剂的研究进展,集中讨论催化剂结构的变化对催化性能的影响. 相似文献
19.
Wen‐Jie Tao Dr. Jun‐Fang Li Ai‐Qing Peng Dr. Xiu‐Li Sun Xiao‐Hong Yang Prof. Dr. Yong Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13956-13961
By a reasonable combination of the Wacker reaction and olefin polymerization processes, water proves to be an excellent activator for the palladium(II)‐catalyzed polymerization of ethylene and it provides a safe, environmental‐friendly and handy initiator for olefin polymerization. The activity of the olefin polymerization is comparable to reactions catalyzed by the corresponding alkylated cationic palladium complexes. 相似文献
20.
Bambirra S Bouwkamp MW Meetsma A Hessen B 《Journal of the American Chemical Society》2004,126(30):9182-9183
Using a sterically demanding amidinate ancillary ligand and an in situ alkylation procedure, neutral mono(amidinate) dialkyl and cationic mono(amidinate) monoalkyl complexes were prepared for metals spanning the full size range of the group 3 and lanthanide metals. The activity of the cationic monoalkyls in catalytic ethene polymerization was found to vary by over 2 orders of magnitude depending on the metal ionic radius, the intermediate metal sizes being found to be the most effective. 相似文献