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Selective Hydrogen Generation from Formic Acid with Well‐Defined Complexes of Ruthenium and Phosphorus–Nitrogen PN3‐Pincer Ligand 下载免费PDF全文
Dr. Yupeng Pan Dr. Cheng‐Ling Pan Yufan Zhang Dr. Huaifeng Li Dr. Shixiong Min Dr. Xunmun Guo Dr. Bin Zheng Dr. Hailong Chen Addison Anders Prof. Zhiping Lai Prof. Junrong Zheng Prof. Kuo‐Wei Huang 《化学:亚洲杂志》2016,11(9):1357-1360
An unsymmetrically protonated PN3‐pincer complex in which ruthenium is coordinated by one nitrogen and two phosphorus atoms was employed for the selective generation of hydrogen from formic acid. Mechanistic studies suggest that the imine arm participates in the formic acid activation/deprotonation step. A long life time of 150 h with a turnover number over 1 million was achieved. 相似文献
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Cover Picture: Selective Hydrogen Generation from Formic Acid with Well‐Defined Complexes of Ruthenium and Phosphorus–Nitrogen PN3‐Pincer Ligand (Chem. Asian J. 9/2016) 下载免费PDF全文
Dr. Yupeng Pan Dr. Cheng‐Ling Pan Yufan Zhang Dr. Huaifeng Li Dr. Shixiong Min Dr. Xunmun Guo Dr. Bin Zheng Dr. Hailong Chen Addison Anders Prof. Zhiping Lai Prof. Junrong Zheng Prof. Kuo‐Wei Huang 《化学:亚洲杂志》2016,11(9):1294-1294
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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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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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Enhanced Hydrogen Generation from Formic Acid by Half‐Sandwich Iridium(III) Complexes with Metal/NH Bifunctionality: A Pronounced Switch from Transfer Hydrogenation 下载免费PDF全文
Asuka Matsunami Prof. Dr. Yoshihito Kayaki Prof. Dr. Takao Ikariya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13513-13517
By switching the catalytic function from transfer hydrogenation based on the metal/NH bifunctionality, facile dehydrogenation of formic acid was achieved by amido‐ and hydrido(amine)–Ir complexes derived from N‐triflyl‐1,2‐diphenylethylenediamine (TfDPEN) at ambient temperature even in the absence of base additives. Further acceleration was observed by the addition of water, leading to a maximum turnover frequency above 6000 h?1. A proton‐relay mechanism guided by the protic amine ligand and water is postulated for effective protonation of metal hydrides. 相似文献
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Baratta W Bossi G Putignano E Rigo P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(12):3474-3481
The ruthenium and osmium complexes [MCl2(diphosphane)(L)] (M=Ru, Os; L=bidentate amino ligand) and [MCl(CNN)(dppb)] (CNN=pincer ligand; dppb=1,4‐bis‐ (diphenylphosphino)butane), containing the N–H moiety, have been found to catalyze the acceptorless dehydrogenation of alcohols in tBuOH and in the presence of KOtBu. The compounds trans‐[MCl2(dppf)(en)] (M=Ru 7 , Os 13 ; dppf=1,1′‐bis(diphenylphosphino)ferrocene; en=ethylenediamine) display very high activity and different substrates, including cyclic and linear alcohols, are efficiently oxidized to ketones by using 0.8–0.04 mol % of catalyst. The effect of the base and the comparison of the catalytic activity of the Ru versus Os complexes are reported. The ruthenium complex 7 generally leads to a faster conversion into ketones with respect to the osmium complex 13 , which displays better activity in the dehydrogenation of 5‐en‐3β‐hydroxy steroids. The synthesis of new Ru and Os complexes [MCl2(PP)(L)] (PP=dppb, dppf; L=(±)‐trans‐1,2‐diaminocyclohexane, 2‐(aminomethyl)pyridine, and 2‐aminoethanol) of trans and cis configuration is also reported. 相似文献
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A Metal–Ligand Cooperative Pathway for Intermolecular Oxa‐Michael Additions to Unsaturated Nitriles 下载免费PDF全文
Sébastien Perdriau Douwe S. Zijlstra Prof. Dr. Hero J. Heeres Prof. Dr. Johannes G. de Vries Dr. Edwin Otten 《Angewandte Chemie (International ed. in English)》2015,54(14):4236-4240
An unprecedented catalytic pathway for oxa‐Michael addition reactions of alcohols to unsaturated nitriles has been revealed using a PNN pincer ruthenium catalyst with a dearomatized pyridine backbone. The isolation of a catalytically competent Ru–dieneamido complex from the reaction between the Ru catalyst and pentenenitrile in combination with DFT calculations supports a mechanism in which activation of the nitrile through metal–ligand cooperativity is a key step. The nitrile‐derived Ru‐N moiety is sufficiently Brønsted basic to activate the alcohol and initiate conjugate addition of the alkoxide to the α,β‐unsaturated fragment. This reaction proceeds in a concerted manner and involves a six‐membered transition state. These features allow the reaction to proceed at ambient temperature in the absence of external base. 相似文献
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Tse MK Bhor S Klawonn M Anilkumar G Jiao H Döbler C Spannenberg A Mägerlein W Hugl H Beller M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(7):1855-1874
The synthesis of chiral tridentate N,N,N-pyridine-2,6-bisoxazolines 3 (pybox ligands) and N,N,N-pyridine-2,6-bisoxazines 4 (pyboxazine ligands) is described in detail. These novel ligands constitute a useful toolbox for the application in asymmetric catalysis. Compounds 3 and 4 are conveniently prepared by cyclization of enantiomerically pure alpha- or beta-amino alcohols with dimethyl pyridine-2,6-dicarboximidate. The corresponding ruthenium complexes are efficient asymmetric epoxidation catalysts and have been prepared in good yield and fully characterized by spectroscopic means. Four of these ruthenium complexes have been characterized by X-ray crystallography. For the first time the molecular structure of a pyboxazine complex [2,6-bis-[(4S)-4-phenyl-5,6-dihydro-4H-[1,3]oxazinyl]pyridine](pyridine-2,6-dicarboxylate)ruthenium (S)-2 aa, is presented. 相似文献
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β‐Hydrogen Elimination Reactions of Nickel and Palladium Methoxides Stabilised by PCP Pincer Ligands 下载免费PDF全文
Dr. Luis M. Martínez‐Prieto Elena Ávila Dr. Pilar Palma Dr. Eleuterio Álvarez Prof. Dr. Juan Cámpora 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9833-9849
Nickel and palladium methoxides [(iPrPCP)M‐OMe], which contain the iPrPCP pincer ligand, decompose upon heating to give products of different kinds. The palladium derivative cleanly gives the dimeric Pd0 complex [Pd(μ‐iPrPCHP)]2 (iPrPCHP=2,6‐bis(diisopropylphosphinomethyl)phenyl) and formaldehyde. In contrast, decomposition of [(iPrPCP)Ni‐OMe] affords polynuclear carbonyl phosphine complexes. Both decomposition processes are initiated by β‐hydrogen elimination (BHE), but the resulting [(iPrPCP)M‐H] hydrides undergo divergent reaction sequences that ultimately lead to the irreversible breakdown of the pincer units. Whereas the Pd hydride spontaneously experiences reductive C?H coupling, the decay of its Ni analogue is brought about by its reaction with formaldehyde released in the BHE step. Kinetic measurements showed that the BHE reaction is reversible and less favourable for Ni than for Pd for both kinetic and thermodynamic reasons. DFT calculations confirmed the main conclusions of the kinetic studies and provided further insight into the mechanisms of the decomposition reactions. 相似文献
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Hydrogen Production from a Methanol–Water Solution Catalyzed by an Anionic Iridium Complex Bearing a Functional Bipyridonate Ligand under Weakly Basic Conditions 下载免费PDF全文
Prof. Dr. Ken‐ichi Fujita Dr. Ryoko Kawahara Takuya Aikawa Prof. Dr. Ryohei Yamaguchi 《Angewandte Chemie (International ed. in English)》2015,54(31):9057-9060
An efficient catalytic system for the production of hydrogen from a methanol–water solution has been developed using a new anionic iridium complex bearing a functional bipyridonate ligand as a catalyst. This system can be operated under mild conditions [weakly basic solution (0.046 mol L?1 NaOH) below 100 °C] without the use of an additional organic solvent. Long‐term continuous hydrogen production from a methanol–water solution catalyzed by the anionic iridium complex was also achieved. 相似文献
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Boopathy Gnanaprakasam Ekambaram Balaraman Chidambaram Gunanathan David Milstein 《Journal of polymer science. Part A, Polymer chemistry》2012,50(9):1755-1765
The amidation reaction based on catalytic coupling of alcohols with amines previously reported by us, using the pincer complexes 1 and 2 as catalysts, was applied to the generation of polyamides from nonactivated diols and diamines. A range of polymers was prepared, with Mn up to 26.9 kDa. Unlike the traditional syntheses of polyamides based on carboxylic acid derivatives, which require the use of toxic reagents and generate stoichiometric amounts of waste, this process generates only molecular hydrogen as byproduct. Both aromatic and aliphatic diols and diamines were used. Gel permeation chromatography measurements of the dimethylformamide‐soluble polymers and thermal studies of the polyamides were performed. Matrix assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) spectra are also reported. Thermogravimetric analyses studies indicate that the aromatic polyamides (with the exception of the pyridine‐based polyamide) are more thermally stable than the aliphatic ones. This general, environmentally benign method for the synthesis of polyamides is homogeneously catalyzed under neutral conditions by dearomatized ruthenium‐pincer complexes 1 and 2 and proceeds in 1,4‐dioxane under an inert atmosphere. Conditions for polyamidation in the absence of solvent are also reported, using the pincer complex 2 as catalyst. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
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Céline Fellay Dr. Ning Yan Dr. Paul J. Dyson Prof. Gábor Laurenczy Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3752-3760
A viable storage system for hydrogen based on selective formic acid decomposition into H2 and CO2 has been developed (see scheme). Continuous generation of H2 of very high purity, over a wide range of pressures and under mild conditions was achieved.
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Dr. Elisabetta Alberico Peter Sponholz Christoph Cordes Dr. Martin Nielsen Dr. Hans‐Joachim Drexler Dr. Wolfgang Baumann Dr. Henrik Junge Prof. Dr. Matthias Beller 《Angewandte Chemie (International ed. in English)》2013,52(52):14162-14166
Molecularly well‐defined iron pincer complexes promote the aqueous‐phase reforming of methanol to carbon dioxide and hydrogen, which is of interest in the context of a methanol and hydrogen economy. For the first time, the use of earth‐abundant iron complexes under mild conditions for efficient hydrogen generation from alcohols is demonstrated. 相似文献
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