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Ruthenium(II) Complexes Containing Lutidine‐Derived Pincer CNC Ligands: Synthesis,Structure, and Catalytic Hydrogenation of CN bonds 下载免费PDF全文
Dr. Martín Hernández‐Juárez Dr. Joaquín López‐Serrano Dr. Patricia Lara Judith P. Morales‐Cerón Dr. Mónica Vaquero Dr. Eleuterio Álvarez Prof. Verónica Salazar Dr. Andrés Suárez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7540-7555
A series of Ru complexes containing lutidine‐derived pincer CNC ligands have been prepared by transmetalation with the corresponding silver‐carbene derivatives. Characterization of these derivatives shows both mer and fac coordination of the CNC ligands depending on the wingtips of the N‐heterocyclic carbene fragments. In the presence of tBuOK, the Ru‐CNC complexes are active in the hydrogenation of a series of imines. In addition, these complexes catalyze the reversible hydrogenation of phenantridine. Detailed NMR spectroscopic studies have shown the capability of the CNC ligand to be deprotonated and get involved in ligand‐assisted activation of dihydrogen. More interestingly, upon deprotonation, the Ru‐CNC complex 5 e (BF4) is able to add aldimines to the metal–ligand framework to yield an amido complex. Finally, investigation of the mechanism of the hydrogenation of imines has been carried out by means of DFT calculations. The calculated mechanism involves outer‐sphere stepwise hydrogen transfer to the C?N bond assisted either by the pincer ligand or a second coordinated H2 molecule. 相似文献
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Anne Landwehr Dr. Balz Dudle Dr. Thomas Fox Dr. Olivier Blacque Prof. Dr. Heinz Berke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(18):5701-5714
The silyloxycyclopentadienyl hydride complexes [Re(H)(NO)(PR3)(C5H4OSiMe2tBu)] (R=iPr ( 3 a ), Cy ( 3 b )) were obtained by the reaction of [Re(H)(Br)(NO)(PR3)2] (R=iPr, Cy) with Li[C5H4OSiMe2tBu]. The ligand–metal bifunctional rhenium catalysts [Re(H)(NO)(PR3)(C5H4OH)] (R=iPr ( 5 a ), Cy ( 5 b )) were prepared from compounds 3 a and 3 b by silyl deprotection with TBAF and subsequent acidification of the intermediate salts [Re(H)(NO)(PR3)(C5H4O)][NBu4] (R=iPr ( 4 a ), Cy ( 4 b )) with NH4Br. In nonpolar solvents, compounds 5 a and 5 b formed an equilibrium with the isomerized trans‐dihydride cyclopentadienone species [Re(H)2(NO)(PR3)(C5H4O)] ( 6 a,b ). Deuterium‐labeling studies of compounds 5 a and 5 b with D2 and D2O showed H/D exchange at the HRe and HO positions. Compounds 5 a and 5 b were active catalysts in the transfer hydrogenation reactions of ketones and imines with 2‐propanol as both the solvent and H2 source. The mechanism of the transfer hydrogenation and isomerization reactions was supported by DFT calculations, which suggested a secondary‐coordination‐sphere mechanism for the transfer hydrogenation of ketones. 相似文献
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Pincer‐Type Complexes for Catalytic (De)Hydrogenation and Transfer (De)Hydrogenation Reactions: Recent Progress 下载免费PDF全文
Dr. Svenja Werkmeister Jacob Neumann Dr. Kathrin Junge Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12226-12250
Pincer complexes are becoming increasingly important for organometallic chemistry and organic synthesis. Since numerous applications for such catalysts have been developed in recent decades, this Minireview covers progress in their use as catalysts for (de)hydrogenation and transfer (de)hydrogenation reactions during the last four years. Aside from noble‐metal‐based pincer complexes, the corresponding base metal complexes are also highlighted and their applications summarized. 相似文献
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Zincocene and Dizincocene N‐Heterocyclic Carbene Complexes and Catalytic Hydrogenation of Imines and Ketones 下载免费PDF全文
Dr. Phillip Jochmann Prof. Dr. Douglas W. Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8370-8378
The N‐heterocyclic carbene (NHC) adducts Zn(CpR)2(NHC)] (CpR=C5HMe4, C5H4SiMe3; NHC=ItBu, IDipp (Dipp=2,6‐diisopropylphenyl), IMes (Mes=mesityl), SIMes) were prepared and shown to be active catalysts for the hydrogenation of imines, whereas decamethylzincocene [ZnCp*2] is highly active for the hydrogenation of ketones in the presence of noncoordinating NHCs. The abnormal carbene complex [Zn(OCHPh2)2(aItBu)]2 was formed from spontaneous rearrangement of the ItBu ligand during incomplete hydrogenation of benzophenone. Two isolated ZnI adducts [Zn2Cp*2(NHC)] (NHC=ItBu, SIMes) are presented and characterized as weak adducts on the basis of 13C NMR spectroscopic and X‐ray diffraction experiments. A mechanistic proposal for the reduction of [ZnCp*2] with H2 to give [Zn2Cp*2] is discussed. 相似文献
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NNP‐Type Pincer Imidazolylphosphine Ruthenium Complexes: Efficient Base‐Free Hydrogenation of Aromatic and Aliphatic Nitriles under Mild Conditions 下载免费PDF全文
Dr. Rosa Adam Dr. Elisabetta Alberico Dr. Wolfgang Baumann Dr. Hans‐Joachim Drexler Dr. Ralf Jackstell Dr. Henrik Junge Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4991-5002
A series of seven novel NImNHP‐type pincer imidazolylphosphine ruthenium complexes has been synthesized and fully characterized. The use of hydrogenation of benzonitrile as a benchmark test identified [RuHCl(CO)(NImNHPtBu)] as the most active catalyst. With its stable Ru?BH4 analogue, in which chloride is replaced by BH4, a broad range of (hetero)aromatic and aliphatic nitriles, including industrially interesting adiponitrile, has been hydrogenated under mild and base‐free conditions. 相似文献
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Facile Protocol for Catalytic Frustrated Lewis Pair Hydrogenation and Reductive Deoxygenation of Ketones and Aldehydes 下载免费PDF全文
Tayseer Mahdi Prof. Dr. Douglas W. Stephan 《Angewandte Chemie (International ed. in English)》2015,54(29):8511-8514
A series of ketones and aldehydes are reduced in toluene under H2 in the presence of 5 mol % B(C6F5)3 and either cyclodextrin or molecular sieves affording a facile metal‐free protocol for reduction to alcohols. Similar treatment of aryl ketones resulted in metal‐free deoxygenation yielding aromatic hydrocarbons. 相似文献
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Kasumi Hayashi Dr. Qiuming Liang Franka Philippi Prof. Dr. Datong Song 《欧洲无机化学杂志》2023,26(21):e202300168
A series of piano-stool Ru−NHC (NHC=N-heterocyclic carbene) complexes have been prepared and characterized. The NHC ligands used herein have varying wingtip groups, showing the impact of steric congestion on the selectivity for the catalytic dimerization of terminal alkynes. 相似文献
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Koji Fukamizu Yoshihiro Miyake Dr. Yoshiaki Nishibayashi Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(14):2534-2537
Another way to dienes : The ruthenium‐catalyzed 6‐endo‐cycloisomerization of 1,5‐enynes gives the corresponding 1,3‐cyclohexadienes in high to excellent yields. This novel synthetic and catalytic method constitutes another way to selectively prepare 1,3‐cyclohexadienes, this cyclic diene skeleton being a core subunit in many natural products and a useful building block for a variety of organic transformations.
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Cornelius T. Martha Anton Heemskerk Jan‐Carel Hoogendoorn Niels Elders Wilfried M. A. Niessen Prof. Dr. Romano V. A. Orru Prof. Dr. Hubertus Irth Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(30):7368-7375
Optimising synthetic conversions and assessing catalyst performance is a tedious and laborious endeavour. Herein, we present an automated alternative to the commonly applied sequential approaches that are used to increase catalyst discovery process efficiencies by increasing the number of entities that can be tested. This new approach combines conversion of the reactants and determination of product formation into a single comprehensive reaction detection system that can be operated with minimal catalyst and reactant consumption. With this approach, rudimentary reaction conditions can be quickly optimised and the same system can then be used to screen for the optimal homogenous catalyst in a selected solution‐phase synthetic conversion. The system, which is composed of standard HPLC components, can be used to screen catalyst libraries at a repetition rate of five minutes and can be run unsupervised. The sensitive mass spectrometric detection that is implemented in the reaction detection methodology can be used for the simultaneous monitoring of reactants, catalysts and product ions. In the experiments, the three‐component reaction that gives a substituted 2‐imidazoline was optimised. Afterwards, the same method was used to assess a library of ferrocene‐based Lewis acid catalysts for performance in the aforementioned conversion in six different solvents. We demonstrate the feasibility of using this methodology to directly compare the performance results obtained in different solvents by calibrating the solvent‐specific MS responses. 相似文献
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Synthesis and Catalytic Water Oxidation Activities of Ruthenium Complexes Containing Neutral Ligands
Dr. Yunhua Xu Lele Duan Dr. Torbjörn Åkermark Lianpeng Tong Bao‐Lin Lee Dr. Rong Zhang Prof. Björn Åkermark Prof. Licheng Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(34):9520-9528
Two dinuclear and one mononuclear ruthenium complexes containing neutral polypyridyl ligands have been synthesised as pre‐water oxidation catalysts and characterised by 1H and 13C NMR spectroscopy and ESI‐MS. Their catalytic water oxidation properties in the presence of [Ce(NH4)2(NO3)6] (CeIV) as oxidant at pH 1.0 have been investigated. At low concentrations of CeIV (5 mM ), high turnover numbers of up to 4500 have been achieved. An 18O‐labelling experiment established that both O atoms in the evolved O2 originate from water. Combined electrochemical study and electrospray ionisation mass spectrometric analysis suggest that ligand exchange between coordinated 4‐picoline and free water produces Ru aquo species as the real water oxidation catalysts. 相似文献
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Renhua Qiu Guoping Zhang Yuyang Zhu Xinhua Xu Lingling Shao Yinhui Li Delie An Shuangfeng Yin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(26):6488-6494
Stable complexes : An extremely air‐stable μ2‐hydroxy‐bridged binuclear hafonocene perfluorooctanesulfoante complex shows high catalytic efficiency in Lewis acid‐catalyzed reactions, such as esterification, Friedel–Crafts acylation, the Mukaiyama aldol reation, and the allylation of aldehyde (see scheme).
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Protic NNN and NCN Pincer‐Type Ruthenium Complexes Featuring (Trifluoromethyl)pyrazole Arms: Synthesis and Application to Catalytic Hydrogen Evolution from Formic Acid 下载免费PDF全文
Yoshiko Nakahara Tatsuro Toda Prof. Dr. Asuka Matsunami Prof. Dr. Yoshihito Kayaki Prof. Dr. Shigeki Kuwata 《化学:亚洲杂志》2018,13(1):73-80
NNN and NCN pincer‐type ruthenium(II) complexes featuring two protic pyrazol‐3‐yl arms with a trifluoromethyl (CF3) group at the 5‐position were synthesized and structurally characterized to evaluate the impact of the substitution on the properties and catalysis. The increased Brønsted acidity by the highly electron‐withdrawing CF3 pendants was demonstrated by protonation–deprotonation experiments. By contrast, the IR spectra of the carbonyl derivatives as well as the cyclic voltammogram indicated that the electron density of the ruthenium atom is negligibly influenced by the CF3 group. Catalysis of these complexes in the decomposition of formic acid to dihydrogen and carbon dioxide was also examined. The NNN pincer‐type complex 1 a with the CF3 group exhibited a higher catalytic activity than the tBu‐substituted analogue 1 b . In addition, the bis(CF3‐pyrazolato) ammine derivative 4 catalyzed the reaction even in the absence of base additives. 相似文献
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