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排序方式: 共有922条查询结果,搜索用时 31 毫秒
911.
Mixed-Valence CuI/CuIII Metal–Organic Frameworks with Non-innocent Ligand for Multielectron Transfer
Shang-Yuan Fu Cheng-Han Chang Dr. Alexander S. Ivanov Dr. Ilja Popovs Dr. Jeng-Lung Chen Dr. Yen-Fa Liao Dr. Hsin-Kuan Liu Dr. Suman Chirra Prof. Dr. Yun-Wei Chiang Jui-Chin Lee Wei-Ling Liu Prof. Dr. Watchareeya Kaveevivitchai Prof. Dr. Teng-Hao Chen 《Angewandte Chemie (International ed. in English)》2023,62(50):e202312494
We report two novel three-dimensional copper-benzoquinoid metal–organic frameworks (MOFs), [Cu4L3]n and [Cu4L3 ⋅ Cu(iq)3]n (LH4=1,4-dicyano-2,3,5,6-tetrahydroxybenzene, iq=isoquinoline). Spectroscopic techniques and computational studies reveal the unprecedented mixed valency in MOFs, formal Cu(I)/Cu(III). This is the first time that formally Cu(III) species are witnessed in metal–organic extended solids. The coordination between the mixed-valence metal and redox-non-innocent ligand L, which promotes through-bond charge transfer between Cu metal sites, allows better metal-ligand orbital overlap of the d-π conjugation, leading to strong long-range delocalization and semiconducting behavior. Our findings highlight the significance of the unique mixed valency between formal Cu(I) and highly-covalent Cu(III), non-innocent ligand, and pore environments of these bench stable Cu(III)-containing frameworks on multielectron transfer and electrochemical properties. 相似文献
912.
Nils Ansmann Joshua Münch Prof. Dr. Marcel Schorpp Prof. Dr. Lutz Greb 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313636
Anionic [Pd(0)−X]− ate complex were proposed as key intermediates in Pd-catalyzed cross-coupling for decades, but their isolation remained elusive. Herein, a chelating Lewis acidic bis(amidophenolato)silane is introduced as a strong Z-type ligand which enables the characterization of the first anionic [Pd(0)−X]− ate complex. Intriguingly, these compounds and the neutral L−Pd(0) analogs exhibit a square planar coordination that is highly unusual for a d10 metal. Theoretical methods scrutinize the interaction between the Lewis acidic Si(IV) center and the late transition metal, while reactivity studies shed light on the potential role of anionic additives in oxidative addition reactions. 相似文献
913.
Jakob Lebon Alexandros Mortis Dr. Cäcilia Maichle-Mössmer Dr. Manfred Manßen Dr. Peter Sirsch Prof. Dr. Reiner Anwander 《Angewandte Chemie (International ed. in English)》2023,62(6):e202214599
Commercially available stock solutions of organolithium reagents are well-implemented tools in organic and organometallic chemistry. However, such solutions are inherently contaminated with lithium halide salts, which can complicate certain synthesis protocols and purification processes. Here, we report the isolation of chloride-free methyllithium employing K[N(SiMe3)2] as a halide-trapping reagent. The influence of distinct LiCl contaminations on the 7Li-NMR chemical shift is examined and their quantification demonstrated. The structural parameters of new chloride-free monomeric methyllithium complex [(Me3TACN)LiCH3], ligated by an azacrown ether, are assessed by comparison with a halide-contaminated variant and monomeric lithium chloride [(Me3TACN)LiCl], further emphasizing the effect of halide impurities. 相似文献
914.
Guilhem Claude Dominik Weh Dr. Adelheid Hagenbach Prof. Joshua S. Figueroa Prof. Ulrich Abram 《无机化学与普通化学杂志》2023,649(1):e202200320
p-Fluorophenylisocyanide (CNPhpF) reacts with [Re(CO)5Br] under stepwise exchange of the carbonyl ligands depending on the conditions applied. The reaction stops with the formation of fac-[Re(CO)3Br(CNPhpF)2] in boiling THF. An ongoing carbonyl exchange is observed at higher temperatures, e. g. in refluxing toluene, with the final formation of the [Re(CNPhpF)6]+ cation. The progress of the reactions has been studied by 19F NMR spectroscopy and the structures of [Re(CO)Br(CNPhpF)4] and [Re(CNPhpF)6](BPh4) have been elucidated by X-ray diffraction. 相似文献
915.
Dr. Van T. Tran Dr. Nana Kim Camille Z. Rubel Xiangyu Wu Taeho Kang Dr. Tanner C. Jankins Zi-Qi Li Dr. Matthew V. Joannou Dr. Sloan Ayers Dr. Milan Gembicky Dr. Jake Bailey Emily J. Sturgell Brittany B. Sanchez Dr. Jason S. Chen Prof. Song Lin Dr. Martin D. Eastgate Dr. Steven R. Wisniewski Prof. Keary M. Engle 《Angewandte Chemie (International ed. in English)》2023,62(9):e202211794
A flurry of recent research has centered on harnessing the power of nickel catalysis in organic synthesis. These efforts have been bolstered by contemporaneous development of well-defined nickel (pre)catalysts with diverse structure and reactivity. In this report, we present ten different bench-stable, 18-electron, formally zero-valent nickel–olefin complexes that are competent pre-catalysts in various reactions. Our investigation includes preparations of novel, bench-stable Ni(COD)(L) complexes (COD=1,5-cyclooctadiene), in which L=quinone, cyclopentadienone, thiophene-S-oxide, and fulvene. Characterization by NMR, IR, single-crystal X-ray diffraction, cyclic voltammetry, thermogravimetric analysis, and natural bond orbital analysis sheds light on the structure, bonding, and properties of these complexes. Applications in an assortment of nickel-catalyzed reactions underscore the complementary nature of the different pre-catalysts within this toolkit. 相似文献
916.
Tian Xie Dr. Lili Chen Dr. Zhenlu Shen Dr. Senmiao Xu 《Angewandte Chemie (International ed. in English)》2023,62(14):e202300199
Reported here is an efficient and simple ether-directed iridium-catalyzed enantioselective C(sp3)−H borylation of cyclopropanes. Various functional groups were well-tolerated, affording a vast array of chiral cyclopropanes with high enantioselectivities. We also demonstrated that the turnover numbers of the current reaction could be up to 335. 相似文献
917.
Dr. Bo Yang Jihui Gao Xingfa Tan Dr. Yicong Ge Prof. Dr. Chuan He 《Angewandte Chemie (International ed. in English)》2023,62(36):e202307812
Catalytic enantioselective intermolecular C−H silylation offers an efficient approach for the rapid construction of chiral organosilicon compounds, but remains a significant challenge. Herein, a new type of chiral silyl ligand is developed, which enables the first iridium-catalyzed atroposelective intermolecular C−H silylation reaction of 2-arylisoquinolines. This protocol features mild reaction conditions, high atom economy, and remarkable yield with excellent stereoselectivity (up to 99 % yield, 99 % ee), delivering enantioenriched axially chiral silane platform molecules with facile convertibility. Key to the success of this unprecedented transformation relies on a novel chiral PSiSi-ligand, which facilitates the intermolecular C−H silylation process with perfect chem-, regio- and stereo-control via a multi-coordinated silyl iridium complex. 相似文献
918.
Chen-Hui Yuan Xiao-Xia Wang Prof. Dr. Lei Jiao 《Angewandte Chemie (International ed. in English)》2023,62(17):e202300854
Amide is one of the most widespread functional groups in organic and bioorganic chemistry, and it would be valuable to achieve stereoselective C(sp3)−H functionalization in amide molecules. Palladium(II) catalysis has been prevalently used in the C−H activation chemistry in the past decades, however, due to the weakly-coordinating feature of simple amides, it is challenging to achieve their direct C(sp3)−H functionalization with enantiocontrol by PdII catalysis. Our group has developed sulfoxide-2-hydroxypridine (SOHP) ligands, which exhibited remarkable activity in Pd-catalyzed C(sp2)−H activation. In this work, we demonstrate that chiral SOHP ligands served as an ideal solution to enantioselective C(sp3)−H activation in simple amides. Herein, we report an efficient asymmetric PdII/SOHP-catalyzed β-C(sp3)−H arylation of aliphatic tertiary amides, in which the SOHP ligand plays a key role in the stereoselective C−H deprotonation-metalation step. 相似文献
919.
Dr. Yu Zhang Dr. Shaobo Han Dr. Shangqian Zhu Dr. Ruhui Chen Tiehuai Li Dr. Zhiheng Lyu Dr. Ming Zhao Prof. Dr. Meng Gu Prof. Dr. Minhua Shao Prof. Dr. Younan Xia 《Angewandte Chemie (International ed. in English)》2023,62(52):e202314634
Surface ligands play an important role in shape-controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.93±0.17 nm in thickness) by simply aging the colloidal suspension. The aged Pd NSs show well-preserved morphology, together with significantly enhanced stability toward both e-beam irradiation and electrocatalysis (e.g., ethanol oxidation). It is revealed that the slow desorption of PVP during aging forces the re-exposed Pd atoms to reorganize, facilitating the surface to transform from being nearly perfect to defect-rich. The resultant Pd NSs with abundant defects no longer rely on surface ligand to stabilize the atomic arrangement and thus show excellent structural and electrochemical stability. This work provides a facile and effective method to maintain the integrity of colloidal nanocrystals by slowly removing the surface ligand. 相似文献
920.
Xuliang Zhang Hehe Huang Lujie Jin Chao Wen Qian Zhao Chenyu Zhao Junjun Guo Chen Cheng Hongshuai Wang Prof. Liang Zhang Prof. Youyong Li Prof. Yin Maung Maung Prof. Jianyu Yuan Prof. Wanli Ma 《Angewandte Chemie (International ed. in English)》2023,62(5):e202214241
For emerging perovskite quantum dots (QDs), understanding the surface features and their impact on the materials and devices is becoming increasingly urgent. In this family, hybrid FAPbI3 QDs (FA: formamidium) exhibit higher ambient stability, near-infrared absorption and sufficient carrier lifetime. However, hybrid QDs suffer from difficulty in modulating surface ligand, which is essential for constructing conductive QD arrays for photovoltaics. Herein, assisted by an ionic liquid formamidine thiocyanate, we report a facile surface reconfiguration methodology to modulate surface and manipulate electronic coupling of FAPbI3 QDs, which is exploited to enhance charge transport for fabricating high-quality QD arrays and photovoltaic devices. Finally, a record-high efficiency approaching 15 % is achieved for FAPbI3 QD solar cells, and they retain over 80 % of the initial efficiency after aging in ambient environment (20–30 % humidity, 25 °C) for over 600 h. 相似文献