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Rüdiger Bertermann Holger Braunschweig Philipp Constantinidis Theresa Dellermann Rian D. Dewhurst William C. Ewing Ingo Fischer Thomas Kramer Jan Mies Ashwini K. Phukan Alfredo Vargas 《Angewandte Chemie (International ed. in English)》2015,54(44):13090-13094
Cation–π interactions are one of the most important classes of noncovalent bonding, and are seen throughout biology, chemistry, and materials science. However, in almost every documented case, these interactions play only a supporting role to much stronger covalent or dative bonds, thus making examples of exclusive cation–π bonding exceedingly rare. In this study, a neutral diboryne molecule is found to encapsulate the light alkali metal cations Li+ and Na+ in the absence of a net charge, covalent bonds, or lone‐pair donor groups. The resulting encapsulation complexes are, to our knowledge, the first structurally authenticated species in which a neutral molecule binds the light alkali metals exclusively through cation–π interactions. 相似文献
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Dr. Shuguang Zhou Jinhu Wang Pei Chen Kehao Chen Prof. Dr. Jin Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14508-14512
A previously elusive RuII‐catalyzed N?N bond‐based traceless C?H functionalization strategy is reported. An N‐amino (i.e., hydrazine) group is used for the directed C?H functionalization with either an alkyne or an alkene, affording an indole derivative or olefination product. The synthesis features a broad substrate scope, superior atom and step economy, as well as mild reaction conditions. 相似文献
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Maria Ortencia Gonzalez Diaz Salvador Lopez Morales Ronan Le Lagadec Larissa Alexandrova 《Journal of polymer science. Part A, Polymer chemistry》2011,49(21):4562-4577
Cationic coordinatively saturated complexes of ruthenium(II), [Ru(o‐C6H4‐2‐py)(phen)(MeCN)2]+, bearing different counterions of PF6? and Cl? have been used in the radical polymerization of 2‐hydroxyethyl methacrylate in protic media and acetone under homogeneous conditions. Exchange of PF6? by Cl? increases the solubility of the complex in water. Both complexes led to the fast polymerization under mild conditions, but control was achieved only in methanol and acetone and was better for the complex with Cl?. The polymerization accelerated in aqueous media and proceeded to a high conversion even with a monomer/catalyst = 2000/1, but without control. Polymerization mediated by complex bearing Cl? was slower in protic solvents but faster in acetone and always resulted in lower molecular weight polymers. Thus, the nature of the anion strongly affected the catalytic activity of the complexes and may serve as way of fine‐tuning the catalytic properties. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
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Govindasamy Vinoth Sekar Indira Madheswaran Bharathi Anandhan Durgadevi Ravikumar Abinaya Luis G. Alves Ana Margarida Martins Kuppannan Shanmuga Bharathi 《应用有机金属化学》2019,33(11)
A new class of half‐sandwich (η6‐p‐cymene) ruthenium(II) complexes supported by 2‐aminofluorene derivatives [Ru(η6‐p‐cymene)(Cl)(L)] ( L = 2‐(((9H‐fluoren‐2‐yl)imino)methyl)phenol ( L 1 ), 2‐(((9H‐fluoren‐2‐yl)imino)methyl)‐3‐methoxyphenol ( L 2 ), 1‐(((9H‐fluoren‐2‐yl)imino)methyl)naphthalene‐2‐ol ( L 3 ) and N‐((1H‐pyrrol‐2‐yl)methylene)‐9H‐fluorene‐2‐amine ( L 4 )) were synthesized. All compounds were fully characterized by analytical and spectroscopic techniques (IR, UV–Vis, NMR) and also by mass spectrometry. The solid state molecular structures of the complexes [Ru(η6‐p‐cymene)(Cl)(L2)], [Ru(η6‐p‐cymene)(Cl)(L3)] and [Ru(η6‐p‐cymene)(Cl)(L4)] revealed that the 2‐aminofluorene and p‐cymene moieties coordinate to ruthenium(II) in a three‐legged piano‐stool geometry. The synthesized complexes were used as catalysts for the dehydrogenative coupling of benzyl alcohol with a range of amines (aliphatic, aromatic and heterocyclic). The reactions were carried out under thermal heating, ultrasound and microwave assistance, using solvent or solvent free conditions, and the catalytic performance was optimized regarding the solvent, the type of base, the catalyst loading and the temperature. Moderately high to very high isolated yields were obtained using [Ru(η6‐p‐cymene)(Cl)(L4)] at 1 mol%. In general, microwave irradiation produced better yields than the other two techniques irrespective of the nature of the substituents. 相似文献
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Structural Diversity in Alkali Metal and Alkali Metal Magnesiate Chemistry of the Bulky 2,6‐Diisopropyl‐N‐(trimethylsilyl)anilino Ligand 下载免费PDF全文
Dr. M. Ángeles Fuentes Andoni Zabala Dr. Alan R. Kennedy Prof. Robert E. Mulvey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):14968-14978
Bulky amido ligands are precious in s‐block chemistry, since they can implant complementary strong basic and weak nucleophilic properties within compounds. Recent work has shown the pivotal importance of the base structure with enhancement of basicity and extraordinary regioselectivities possible for cyclic alkali metal magnesiates containing mixed n‐butyl/amido ligand sets. This work advances alkali metal and alkali metal magnesiate chemistry of the bulky arylsilyl amido ligand [N(SiMe3)(Dipp)]? (Dipp=2,6‐iPr2‐C6H3). Infinite chain structures of the parent sodium and potassium amides are disclosed, adding to the few known crystallographically characterised unsolvated s‐block metal amides. Solvation by N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA) or N,N,N′,N′‐tetramethylethylenediamine (TMEDA) gives molecular variants of the lithium and sodium amides; whereas for potassium, PMDETA gives a molecular structure, TMEDA affords a novel, hemi‐solvated infinite chain. Crystal structures of the first magnesiate examples of this amide in [MMg{N(SiMe3)(Dipp)}2(μ‐nBu)]∞ (M=Na or K) are also revealed, though these breakdown to their homometallic components in donor solvents as revealed through NMR and DOSY studies. 相似文献
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采用自由配体法,将铁邻菲啰啉(Fe(phen)3)配合物封装在含有不同碱金属阳离子的Y型分子筛中,制备了系列Fe(phen)3/M-Y(M=Li+,Na+,K+和Cs+)催化剂.采用X射线衍射、红外光谱、紫外-可见光谱、热重-差热分析、电感耦合等离子原子发射光谱、N2吸附-脱附以及催化氧化反应考察了碱金属离子对Fe(phen)3/M-Y催化剂物化性质和催化氧化性能的影响.结果表明,交换有不同碱金属离子的Y型沸石中Fe(phen)3的封装量不同,而且Fe(phen)3在Y型沸石中的热稳定性随着碱金属离子半径的增加有所降低,其中Fe(phen)3/Li+-Y具有最高的配合物封装量和热稳定性能.在环己烷或苯乙烯氧化反应中,在较低的反应温度下,Fe(phen)3/K+-Y表现出最高的催化活性,而在较高的反应温度下,Fe(phen)3/Cs+-Y的催化活性最高,碱金属离子对Fe(phen)3/M-Y催化氧化性能的影响是电子效应、空间限制作用和扩散效应的综合结果. 相似文献
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Hironobu Ozawa Dr. Masayuki Kobayashi Bijitha Balan Dr. Shigeyuki Masaoka Dr. Ken Sakai Prof. Dr. 《化学:亚洲杂志》2010,5(8):1860-1869
The mechanism of photoinduced hydrogen evolution from water driven by the first photo‐hydrogen‐evolving molecular catalyst ( 1 ), given by a coupling of [Ru(bpy)2(5‐amino‐phen)]2+ and [PtCl2(4,4′‐dicarboxy‐bpy)] (bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline), was investigated in detail. The H2 evolution rate was found to obey Michaelis–Menten enzymatic kinetics with regard to the concentration of EDTA (ethylenediamine tetra‐acetic acid disodium salt, sacrificial electron donor), which indicates that an ion‐pair formation between the dicationic 1 and the dianionic form of EDTA (pH 5) is a key step leading to H2 formation. A 2:1 coupling product of 1 and ethylenediamine (i.e., a {RuII2PtII2} complex 2 ) was found to show significantly higher photo‐hydrogen‐evolving (PHE) activity than 1 , which revealed the validity of the bimolecular activation proposed in our previous study. The PHE activity of 2 was also observed to be linear to the concentration of 2 , which indicates that H2 formation through the intermolecular path competes with the intramolecular path. Molecular orbital diagrams, conformational features, and Pt???H(water or acetic acid) hydrogen bonds were characterized by DFT calculations. 相似文献
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Torben Rogge Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2019,58(44):15640-15645
Experimental and computational studies provide detailed insight into the selectivity‐ and reactivity‐controlling factors in bifurcated ruthenium‐catalyzed direct C?H arylations and dehydrogenative C?H/C?H functionalizations. Thorough investigations revealed the importance of arene‐ligand‐free complexes for the formation of biscyclometalated intermediates within a ruthenium(II/IV/II) mechanistic manifold. 相似文献
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Kai Xiong Chen Qian Yixian Yuan Lin Wei Xinxing Liao Liting He Thomas W. Rees Yu Chen Jian Wan Liangnian Ji Hui Chao 《Angewandte Chemie (International ed. in English)》2020,59(38):16631-16637
Inducing necroptosis in cancer cells is an effective approach to circumvent drug‐resistance. Metal‐based triggers have, however, rarely been reported. Ruthenium(II) complexes containing 1,1‐(pyrazin‐2‐yl)pyreno[4,5‐e][1,2,4]triazine were developed with a series of different ancillary ligands ( Ru1 ‐ 7 ). The combination of the main ligand with bipyridyl and phenylpyridyl ligands endows Ru7 with superior nucleus‐targeting properties. As a rare dual catalytic inhibitor, Ru7 effectively inhibits the endogenous activities of topoisomerase (topo) I and II and kills cancer cells by necroptosis. The cell signaling pathway from topo inhibition to necroptosis was elucidated. Furthermore, Ru7 displays significant antitumor activity against drug‐resistant cancer cells in vivo. To the best of our knowledge, Ru7 is the first Ru‐based necroptosis‐inducing chemotherapeutic agent. 相似文献
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Ruthenium(II) Phthalocyaninates(2–): Synthesis and Properties of (Acido)(carbonyl)phthalocyaninato(2–)ruthenate(II), [Ru(X)(CO)Pc2?]? (X = Cl, Br, I, NCO, NCS, N3) (nBu4N)[Ru(OH)2Pc2?] is reduced in acetone with carbonmonoxid to blue-violet [Ru(H2O)(CO)Pc2?], which yields in tetrahydrofurane with excess (nBu4N)X acido(carbonyl)phthalocyaninato(2–)ruthenate(II), [Ru(X)(CO)Pc2?]? (X = Cl, Br, I, NCO, NCS, N3) isolated as red-violet, diamagnetic (nBu4N) complex salt. The UV-Vis spectra are dominated by the typical π-π* transitions of the Pc2? ligand at approximately 15100 (B), 28300 (Q1) und 33500 cm?1 (Q2), only fairly dependent of the axial ligands. v(C? O) is observed at 1927 (X = I), 1930 (Cl, Br), 1936 (N3, NCO) 1948 cm?1 (NCS), v(C? N) at 2208 cm?1 (NCO), 2093 cm?1 (NCS) and v(N? N) at 2030 cm?1 only in the MIR spectrum. v(Ru? C) coincides in the FIR spectrum with a deformation vibration of the Pc ligand, but is detected in the resonance Raman(RR) spectrum at 516 (X = Cl), 512 (Br), 510 (N3), 504 (I), 499 (NCO), 498 cm?1 (NCS). v(Ru? X) is observed in the FIR spectrum at 257 (X = Cl), 191 (Br), 166 (I), 349 (N3), 336 (NCO) and 224 cm?1 (NCS). Only v(Ru? I) is RR-enhanced. 相似文献
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Distal Weak Coordination of Acetamides in Ruthenium(II)‐Catalyzed C−H Activation Processes 下载免费PDF全文
Qingqing Bu Torben Rogge Dr. Vladislav Kotek Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(3):765-768
C?H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C?H functionalization offers ample scope—including twofold oxidative C?H functionalizations and alkyne hydroarylations—through facile base‐assisted internal electrophilic‐type substitution (BIES) C?H ruthenation by weak O‐coordination. 相似文献
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Catalytic Water Oxidation by Ruthenium(II) Quaterpyridine (qpy) Complexes: Evidence for Ruthenium(III) qpy‐N,N′′′‐dioxide as the Real Catalysts 下载免费PDF全文
Yingying Liu Dr. Siu‐Mui Ng Dr. Shek‐Man Yiu Dr. William W. Y. Lam Xi‐Guang Wei Dr. Kai‐Chung Lau Prof. Tai‐Chu Lau 《Angewandte Chemie (International ed. in English)》2014,53(52):14468-14471
Polypyridyl and related ligands have been widely used for the development of water oxidation catalysts. Supposedly these ligands are oxidation‐resistant and can stabilize high‐oxidation‐state intermediates. In this work a series of ruthenium(II) complexes [Ru(qpy)(L)2]2+ (qpy=2,2′:6′,2′′:6′′,2′′′‐quaterpyridine; L=substituted pyridine) have been synthesized and found to catalyze CeIV‐driven water oxidation, with turnover numbers of up to 2100. However, these ruthenium complexes are found to function only as precatalysts; first, they have to be oxidized to the qpy‐N,N′′′‐dioxide (ONNO) complexes [Ru(ONNO)(L)2]3+ which are the real catalysts for water oxidation. 相似文献
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Wanhua Wu Shaomin Ji Wenting Wu Jingyin Shao Dr. Huimin Guo Prof. Tony D. James Prof. Jianzhang Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(16):4953-4964
RuII–bis‐pyridine complexes typically absorb below 450 nm in the UV spectrum and their molar extinction coefficients are only moderate (ε<16 000 M ?1 cm?1). Thus, RuII–polyimine complexes that show intense visible‐light absorptions are of great interest. However, no effective light‐harvesting ruthenium(II)/organic chromophore arrays have been reported. Herein, we report the first visible‐light‐harvesting RuII–coumarin arrays, which absorb at 475 nm (ε up to 63 300 M ?1 cm?1, 4‐fold higher than typical RuII–polyimine complexes). The donor excited state in these arrays is efficiently converted into an acceptor excited state (i.e., efficient energy‐transfer) without losses in the phosphorescence quantum yield of the acceptor. Based on steady‐state and time‐resolved spectroscopy and DFT calculations, we proposed a general rule for the design of RuII–polypyridine–chromophore light‐harvesting arrays, which states that the 1IL energy level of the ligand must be close to the respective energy level of the metal‐to‐ligand charge‐transfer (M LCT) states. Lower energy levels of 1IL/3IL than the corresponding 1M LCT/3M LCT states frustrate the cascade energy‐transfer process and, as a result, the harvested light energy cannot be efficiently transferred to the acceptor. We have also demonstrated that the light‐harvesting effect can be used to improve the upconversion quantum yield to 15.2 % (with 9,10‐diphenylanthracene as a triplet‐acceptor/annihilator), compared to the parent complex without the coumarin subunit, which showed an upconversion quantum yield of only 0.95 %. 相似文献
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Kojirou Fuku Dr. Takashi Kamegawa Dr. Kohsuke Mori Prof. Hiromi Yamashita 《化学:亚洲杂志》2012,7(6):1366-1371
A simple and practical technique to synthesize nanosized platinum particles loaded on TiO2 (Pt–TiO2) by using a microwave (Mw)‐assisted deposition method has been exploited in the development of a highly efficient photocatalyst for the formation of H2 and N2 gases from harmful nitrogen‐containing chemical wastes, for example, aqueous ammonia (NH3). Upon Mw irradiation, a platinum precursor can be deposited quickly on the TiO2 surface from an aqueous solution of platinum and subsequent reduction with H2 affords the nanosized platinum metal particles with a narrow size distribution (Mw‐Pt–TiO2). Characterization by CO adsorption, platinum LIII‐edge X‐ray absorption fine structure analysis, and TEM analysis revealed that the size of the metal nanoparticles strongly depended on the preparation methods. Smaller platinum nanoparticles were obtained by the Mw heating method than those obtained by conventional preparation techniques, such as photoassisted deposition (PAD), impregnation (Imp), and equilibrium adsorption (EA) deposition by conventional convective heating. The H2 and N2 formation rates increased with increasing dispersity of platinum. Pt–TiO2 prepared by the Mw heating method exhibited a specifically high H2 formation activity in the photocatalytic decomposition of aqueous NH3 in a nearly stoichiometric 3:1 (H2/N2) molar ratio under inert conditions. The present Mw heating method is applicable to a variety of anatase‐type TiO2 species possessing different specific surface areas to provide small and highly dispersed platinum nanoparticles with a narrow size distribution. 相似文献
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Surprisingly Different Reaction Behavior of Alkali and Alkaline Earth Metal Bis(trimethylsilyl)amides toward Bulky N‐(2‐Pyridylethyl)‐N′‐(2,6‐diisopropylphenyl)pivalamidine 下载免费PDF全文
Diana Kalden Ansgar Oberheide Dr. Claas Loh Dr. Helmar Görls Dr. Sven Krieck Prof. Dr. Matthias Westerhausen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10944-10959
N‐(2,6‐Diisopropylphenyl)‐N′‐(2‐pyridylethyl)pivalamidine (Dipp‐N=C(tBu)‐N(H)‐C2H4‐Py) ( 1 ), reacts with metalation reagents of lithium, magnesium, calcium, and strontium to give the corresponding pivalamidinates [(tmeda)Li{Dipp‐N=C(tBu)‐N‐C2H4‐Py}] ( 6 ), [Mg{Dipp‐N=C(tBu)‐N‐C2H4‐Py}2] ( 3 ), and heteroleptic [{(Me3Si)2N}Ae{Dipp‐N=C(tBu)‐N‐C2H4‐Py}], with Ae being Ca ( 2 a ) and Sr ( 2 b ). In contrast to this straightforward deprotonation of the amidine units, the reaction of 1 with the bis(trimethylsilyl)amides of sodium or potassium unexpectedly leads to a β‐metalation and an immediate deamidation reaction yielding [(thf)2Na{Dipp‐N=C(tBu)‐N(H)}] ( 4 a ) or [(thf)2K{Dipp‐N=C(tBu)‐N(H)}] ( 4 b ), respectively, as well as 2‐vinylpyridine in both cases. The lithium derivative shows a similar reaction behavior to the alkaline earth metal congeners, underlining the diagonal relationship in the periodic table. Protonation of 4 a or the metathesis reaction of 4 b with CaI2 in tetrahydrofuran yields N‐(2,6‐diisopropylphenyl)pivalamidine (Dipp‐N=C(tBu)‐NH2) ( 5 ), or [(thf)4Ca{Dipp‐N=C(tBu)‐N(H)}2] ( 7 ), respectively. The reaction of AN(SiMe3)2 (A=Na, K) with less bulky formamidine Dipp‐N=C(H)‐N(H)‐C2H4‐Py ( 8 ) leads to deprotonation of the amidine functionality, and [(thf)Na{Dipp‐N=C(H)‐N‐C2H4‐Py}]2 ( 9 a ) or [(thf)K{Dipp‐N=C(H)‐N‐C2H4‐Py}]2 ( 9 b ), respectively, are isolated as dinuclear complexes. From these experiments it is obvious, that β‐metalation/deamidation of N‐(2‐pyridylethyl)amidines requires bases with soft metal ions and also steric pressure. The isomeric forms of all compounds are verified by single‐crystal X‐ray structure analysis and are maintained in solution. 相似文献