共查询到19条相似文献,搜索用时 187 毫秒
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1968年(O)fele Wanzlick首次合成了N-杂环卡宾金属配合物,但是没有引起人们的重视[1-2],直到1991年Arduengo得到了稳定的N-杂环卡宾,才引起化学界的广泛注意与重视[3].随后,Herrmann等人将N-杂环卡宾金属配合物应用在催化领域,如烯烃复分解反应、偶联反应、硅氢化反应、烯烃氢甲酰化反应、炔烃聚合反应、烯烃环丙化反应、芳基硼酸对醛的加成反应、醛的烯丙基化反应等[4]. 相似文献
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由于N-杂环卡宾配体(NHCs)的独特性能,N-杂环卡宾过渡金属配合物在均相催化等方面取得了重要应用,但是其合成方法却发展缓慢。本文综述了N-杂环卡宾过渡金属配合物合成方法的最新研究进展,介绍了富电子烯烃裂解反应、游离NHC直接配位反应、配体底物的脱质子原位反应、卡宾加合物热解反应、金属交换转移反应和C2-X(X为甲基、卤原子或氢原子)键氧化加成反应等合成N-杂环卡宾过渡金属配合物的主要方法,此外本课题组还首次发现了金属粉末法,该法可用于规模化合成铁、钴、镍、铜等第一过渡系金属NHC配合物。 相似文献
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铜N-杂环卡宾化合物的合成及其在有机合成中的应用 总被引:1,自引:1,他引:0
N-杂环卡宾铜化合物具有简便易得,价廉低毒,性质稳定,结构类型多样并易于修饰等诸多优点,在很多领域具有重要的应用价值,因此铜的N-杂环卡宾化学在过去十几年中得到了快速发展。本文结合我们的工作,总结铜N-杂环卡宾化合物的合成方法、结构特点、转移卡宾配体用于合成其它金属卡宾化合物以及催化应用。 相似文献
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由于其强给电子能力、结构易修饰性和拓扑学特性,N-杂环卡宾成为继有机膦配体之后又一类重要的配体。其金属络合物在均相及不对称催化领域的催化性能是近期研究的热点,已有许多成功的结果。本文综述了近年来N-杂环卡宾及其金属络合物以及N-杂环卡宾的重要前体咪唑盐的合成方法。金属-N-杂环卡宾络合物的合成方法包括:(a)游离卡宾与金属化合物直接络合;(b)咪唑盐与金属化合物在强碱作用下络合;(c)利用Ag-NHC通过卡宾配体转移方法制备新的金属络合物。关于N-杂环卡宾前体的合成途径主要有:(a)乙二醛、伯胺和多聚甲醛的缩合反应;(b)卤代烷与咪唑及其取代咪唑的烷基化反应;(c)原甲酸酯与1,2-二胺的成环反应;(d)肼或酰胺与酸酐的环化反应;(e)用Na/K对环硫脲化合物的还原反应。 相似文献
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N-杂环卡宾金属配合物具有良好的化学稳定性和催化活性,一直是有机化学研究领域中的热点.咪唑盐作为N-杂环卡宾的前体,其制备容易,结构多样的特点为构建拓扑结构的N-杂环卡宾金属配合物提供了基础.主要针对近年来由环状多咪唑盐、非环状多咪唑盐为配体与金属进行组装,或以咪唑盐与P/N配体与金属共同组装,或经过异腈分布合成法形成的具有特殊柱状、笼状、环状、"分子方"和"分子矩形"等结构的多N-杂环卡宾金属配合物的合成,结构及物理化学性质进行归纳总结,并对其研究前景进行了展望. 相似文献
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《Journal of organometallic chemistry》2006,691(24-25):5505-5512
N-heterocyclic carbene (NHC) ligands are a versatile and useful class of ligands that have enjoyed much success over the past few decades in organometallic chemistry. This fact is exemplified most convincingly in Grubbs 2nd generation olefin metathesis catalysts. We explore the electronic impact of the NHC-ligand by decoupling electronic and steric effects through simplified model N-heterocyclic carbenes. Saturated and unsaturated N-heterocyclic carbene ligands give rise to fundamentally different frontier orbitals in these catalysts, suggesting a need to classify them as two electronically distinct ligand classes. 相似文献
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Stefan Czarnocki Louis Monsigny Micha Sienkiewicz Anna Kajetanowicz Karol Grela 《Molecules (Basel, Switzerland)》2021,26(17)
A modular and flexible strategy towards the synthesis of N-heterocyclic carbene (NHC) ligands bearing Brønsted base tags has been proposed and then adopted in the preparation of two tagged NHC ligands bearing rests of isonicotinic and 4-(dimethylamino)benzoic acids. Such tagged NHC ligands represent an attractive starting point for the synthesis of olefin metathesis ruthenium catalysts tagged in non-dissociating ligands. The influence of the Brønsted basic tags on the activity of such obtained olefin metathesis catalysts has been studied. 相似文献
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The asymmetric synthesis of [7]helicene was accomplished in good ee (80%) by kinetic resolution by means of asymmetric olefin metathesis. Three key factors contributed to the success of the kinetic resolution: the use of new Ru-based olefin metathesis catalysts bearing C1-symmetric N-heterocyclic carbene ligands, simple olefins as additives to control the nature of the propagating alkylidene and hexafluorobenzene as a solvent. 相似文献
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Chelated ruthenium catalysts for Z-selective olefin metathesis 总被引:1,自引:0,他引:1
We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands that catalyze highly Z-selective olefin metathesis. A very simple and convenient procedure for the synthesis of such catalysts has been developed. Intramolecular C-H bond activation of the NHC ligand, promoted by anion ligand substitution, forms the appropriate chelate for stereocontrolled olefin metathesis. 相似文献
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Urbano J Hormigo AJ de Frémont P Nolan SP Díaz-Requejo MM Pérez PJ 《Chemical communications (Cambridge, England)》2008,(6):759-761
Styrene can be polymerized at room temperature in the presence of equimolar mixtures of the gold(III) complexes (NHC)AuBr3 (NHC = N-heterocyclic carbene ligand) and NaBAr'4, in the first example of a gold-induced olefin polymerization reaction. 相似文献
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Simal F Delfosse S Demonceau A Noels AF Denk K Kohl FJ Weskamp T Herrmann WA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(13):3047-3052
Air-stable and readily available ruthenium benzylidene complexes of the general type [RuCl2(=CHPh)(L)(L')] (L, L' = PCy3 and/or N-heterocyclic carbene) constitute a new class of catalyst precursors for atom-transfer radical polymerization (ATRP) of methyl methacrylate and styrene, and provide an unprecedented example for the involvement of ruthenium alkylidenes in radical reactions. They promote the polymerization of various monomers with good to excellent yields, and in a controlled way with methyl methacrylate and styrene. Variations of their basic structural motif provide insights into the essential parameters responsible for catalytic activity. The ligands L (PCy3 and/or N-heterocyclic carbene) turned out to play a particularly important role in determining the rate of the polymerizations. A similarly pronounced influence is exerted by the substituents on the N-heterocyclic carbene. Our results indicate that the catalysts decompose quickly under ATRP conditions, and polymerizations are mediated by both [RuCl2(=CHPh)(L)(L')] complexes and ruthenium species bereft of the benzylidene moiety, through a pathway in which both tricyclohexylphosphane and/or N-heterocyclic carbene ligands remain bound to the metal center. Polymerization of n-butyl acrylate and vinyl acetate is not controlled and most probably takes place through a redox-initiated free-radical process. 相似文献
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The synthesis, structure, and performance of new ruthenium-based olefin metathesis catalysts, featuring fluorinated NHC ligands are presented. The introduction of halogen atoms into the N-heterocyclic carbene ligand profoundly alters the catalytic activity and can afford a more efficient catalyst. Structural investigations suggest that a fluorine-ruthenium interaction is responsible for this increased activity. 相似文献
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烯烃聚合催化剂的设计是烯烃配位聚合领域的一个核心科学问题,通过设计合成精确结构的催化剂可以有效地调控催化聚合性能以及聚合产物的结构.后过渡金属催化剂由于其易调变性、对聚合产物支化结构的可控性及对极性单体的容忍性,在烯烃聚合领域引起了广泛的关注.本文介绍了近年来本课题组在[N,N]-二齿镍烯烃聚合催化剂设计方面的研究进展,包括四元环的中性脒基镍催化剂、五元环的-二亚胺镍催化剂、2-胺基吡啶和-胺基亚胺系列镍催化剂,以及六元环的-二亚胺和苯胺基亚胺镍催化剂在烯烃聚合的应用.通过优化后过渡金属镍催化剂结构,可成功实施烯烃活性聚合. 相似文献