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1.
Ketimido Metallophthalocyanines: An Approach to Phthalocyanine‐Supported Mononuclear High‐Valent Ruthenium Complexes 下载免费PDF全文
Dr. Jie‐Sheng Huang Dr. Kwok‐Ming Wong Dr. Sharon Lai‐Fung Chan Ken Chi‐Hang Tso Tao Jiang Prof. Dr. Chi‐Ming Che 《化学:亚洲杂志》2014,9(1):338-350
A “metal–ketimine+ArI(OR)2” approach has been developed for preparing metal–ketimido complexes, and ketimido ligands are found to stabilize high‐valent metallophthalocyanine (M? Pc) complexes such as ruthenium(IV) phthalocyanines. Treatment of bis(ketimine) ruthenium(II) phthalocyanines [RuII(Pc)(HN?CPh2)2] ( 1a ) and [RuII(Pc)(HNQu)2] ( 1b ; HNQu=N‐phenyl‐1,4‐benzoquinonediimine) with PhI(OAc)2 affords bis(ketimido) ruthenium(IV) phthalocyanines [RuIV(Pc)(N?CPh2)2] ( 2a ) and [RuIV(Pc)(NQu)2] ( 2b ), respectively. X‐ray crystal structures of 1b and [RuII(Pc)(PhN?CHPh)2] ( 1c ) show Ru? N(ketimine) distances of 2.075(4) and 2.115(3) Å, respectively. Complexes 2a , 2b readily revert to 1a , 1b upon treatment with phenols. 1H NMR spectroscopy reveals that 2a , 2b are diamagnetic and 2b exists as two isomers, consistent with a proposed eclipsed orientation of the ketimido ligands in these ruthenium(IV) complexes. The reaction of 1a , 1b with PhI(OAc)2 to afford 2a , 2b suggests the utility of ArI(OR)2 as an oxidative deprotonation agent for the generation of high‐valent metal complexes featuring M? N bonds with multiple bonding characters. DFT and time‐dependent (TD)‐DFT calculations have been performed on the electronic structures and the UV/Vis absorption spectra of 1b and 2b , which provide support for the diamagnetic nature of 2b and reveal a significant barrier for rotation of the ketimido group about the Ru? N(ketimido) bond. 相似文献
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Ferran Acuña‐Parés Zoel Codolà Dr. Miquel Costas Dr. Josep M. Luis Dr. Julio Lloret‐Fillol 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(19):5696-5707
Density functional theory (DFT) is employed to: 1) propose a viable catalytic cycle consistent with our experimental results for the mechanism of chemically driven (CeIV) O2 generation from water, mediated by nonheme iron complexes; and 2) to unravel the role of the ligand on the nonheme iron catalyst in the water oxidation reaction activity. To this end, the key features of the water oxidation catalytic cycle for the highly active complexes [Fe(OTf)2(Pytacn)] (Pytacn: 1‐(2′‐pyridylmethyl)‐4,7‐dimethyl‐1,4,7‐triazacyclononane; OTf: CF3SO3?) ( 1 ) and [Fe(OTf)2(mep)] (mep: N,N′‐bis(2‐pyridylmethyl)‐N,N′‐dimethyl ethane‐1,2‐diamine) ( 2 ) as well as for the catalytically inactive [Fe(OTf)2(tmc)] (tmc: N,N′,N′′,N′′′‐tetramethylcyclam) ( 3 ) and [Fe(NCCH3)(MePy2CH‐tacn)](OTf)2 (MePy2CH‐tacn: N‐(dipyridin‐2‐yl)methyl)‐N′,N′′‐dimethyl‐1,4,7‐triazacyclononane) ( 4 ) were analyzed. The DFT computed catalytic cycle establishes that the resting state under catalytic conditions is a [FeIV(O)(OH2)(LN4)]2+ species (in which LN4=Pytacn or mep) and the rate‐determining step is the O?O bond‐formation event. This is nicely supported by the remarkable agreement between the experimental (ΔG≠=17.6±1.6 kcal mol?1) and theoretical (ΔG≠=18.9 kcal mol?1) activation parameters obtained for complex 1 . The O?O bond formation is performed by an iron(V) intermediate [FeV(O)(OH)(LN4)]2+ containing a cis‐FeV(O)(OH) unit. Under catalytic conditions (CeIV, pH 0.8) the high oxidation state FeV is only thermodynamically accessible through a proton‐coupled electron‐transfer (PCET) process from the cis‐[FeIV(O)(OH2)(LN4)]2+ resting state. Formation of the [FeV(O)(LN4)]3+ species is thermodynamically inaccessible for complexes 3 and 4 . Our results also show that the cis‐labile coordinative sites in iron complexes have a beneficial key role in the O?O bond‐formation process. This is due to the cis‐OH ligand in the cis‐FeV(O)(OH) intermediate that can act as internal base, accepting a proton concomitant to the O?O bond‐formation reaction. Interplay between redox potentials to achieve the high oxidation state (FeV?O) and the activation energy barrier for the following O?O bond formation appears to be feasible through manipulation of the coordination environment of the iron site. This control may have a crucial role in the future development of water oxidation catalysts based on iron. 相似文献
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Photocatalytic Water Oxidation by a Mixed‐Valent MnIII3MnIVO3 Manganese Oxo Core that Mimics the Natural Oxygen‐Evolving Center 下载免费PDF全文
Dr. Rami Al‐Oweini Dr. Andrea Sartorel Dr. Bassem S. Bassil Dr. Mirco Natali Dr. Serena Berardi Prof. Franco Scandola Prof. Ulrich Kortz Prof. Marcella Bonchio 《Angewandte Chemie (International ed. in English)》2014,53(42):11182-11185
The functional core of oxygenic photosynthesis is in charge of catalytic water oxidation by a multi‐redox MnIII/MnIV manifold that evolves through five electronic states (Si , where i=0–4). The synthetic model system of this catalytic cycle and of its S0→S4 intermediates is the expected turning point for artificial photosynthesis. The tetramanganese‐substituted tungstosilicate [MnIII3MnIVO3(CH3COO)3(A‐α‐SiW9O34)]6? (Mn4POM) offers an unprecedented mimicry of the natural system in its reduced S0 state; it features a hybrid organic–inorganic coordination sphere and is anchored on a polyoxotungstate. Evidence for its photosynthetic properties when combined with [Ru(bpy)3]2+ and S2O82? is obtained by nanosecond laser flash photolysis; its S0→S1 transition within milliseconds and multiple‐hole‐accumulating properties were studied. Photocatalytic oxygen evolution is achieved in a buffered medium (pH 5) with a quantum efficiency of 1.7 %. 相似文献
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Inside Cover: Ketimido Metallophthalocyanines: An Approach to Phthalocyanine‐Supported Mononuclear High‐Valent Ruthenium Complexes (Chem. Asian J. 1/2014) 下载免费PDF全文
Dr. Jie‐Sheng Huang Dr. Kwok‐Ming Wong Dr. Sharon Lai‐Fung Chan Ken Chi‐Hang Tso Tao Jiang Prof. Dr. Chi‐Ming Che 《化学:亚洲杂志》2014,9(1):2-2
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Mononuclear Nonheme Iron(III)‐Iodosylarene and High‐Valent Iron‐Oxo Complexes in Olefin Epoxidation Reactions 下载免费PDF全文
Dr. Bin Wang Dr. Yong‐Min Lee Dr. Mi Sook Seo Prof. Dr. Wonwoo Nam 《Angewandte Chemie (International ed. in English)》2015,54(40):11740-11744
High‐spin iron(III)‐iodosylarene complexes are highly reactive in the epoxidation of olefins, in which epoxides are formed as the major products with high stereospecificity and enantioselectivity. The reactivity of the iron(III)‐iodosylarene intermediates is much greater than that of the corresponding iron(IV)‐oxo complex in these reactions. The iron(III)‐iodosylarene species—not high‐valent iron(IV)‐oxo and iron(V)‐oxo species—are also shown to be the active oxidants in catalytic olefin epoxidation reactions. The present results are discussed in light of the long‐standing controversy on the one oxidant versus multiple oxidants hypothesis in oxidation reactions. 相似文献
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Diego Moreno Gerardo Martínez‐Guajardo Dr. Andrés Díaz‐Celaya Dr. José M. Mercero Prof. Romeo de Coss Dr. Nancy Perez‐Peralta Prof. Gabriel Merino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12668-12672
The potential energy surface of C6Li6 was re‐examined and a new non‐symmetric global minimum was found. The new structure can be described as three C22? fragments strongly aggregated through lithium bridges. At high temperatures, fluxionality is perceived instead of dissociation. At 600 and 900 K, the BOMD simulations show that the lithium mobility is high, indicating that the cluster behaves in a liquid‐like manner (BOMD=Born–Oppenheimer molecular dynamics). 相似文献
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Cory M. Weinstein Dr. Caleb D. Martin Liu Liu Prof. Guy Bertrand 《Angewandte Chemie (International ed. in English)》2014,53(25):6550-6553
By utilizing stable carbenes with low‐lying LUMOs, coupling with the stable nucleophilic diaminocyclopropenylidene was achieved. This reaction resulted in the formation of two new and rare examples of a bent allene as well as the isolation of the first carbene–carbene heterodimer. 相似文献
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A Dinuclear Ruthenium‐Based Water Oxidation Catalyst: Use of Non‐Innocent Ligand Frameworks for Promoting Multi‐Electron Reactions 下载免费PDF全文
Tanja M. Laine Dr. Markus D. Kärkäs Prof. Dr. Rong‐Zhen Liao Prof. Per E. M. Siegbahn Prof. Björn Åkermark 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(28):10039-10048
Insight into how H2O is oxidized to O2 is envisioned to facilitate the rational design of artificial water oxidation catalysts, which is a vital component in solar‐to‐fuel conversion schemes. Herein, we report on the mechanistic features associated with a dinuclear Ru‐based water oxidation catalyst. The catalytic action of the designed Ru complex was studied by the combined use of high‐resolution mass spectrometry, electrochemistry, and quantum chemical calculations. Based on the obtained results, it is suggested that the designed ligand scaffold in Ru complex 1 has a non‐innocent behavior, in which metal–ligand cooperation is an important part during the four‐electron oxidation of H2O. This feature is vital for the observed catalytic efficiency and highlights that the preparation of catalysts housing non‐innocent molecular frameworks could be a general strategy for accessing efficient catalysts for activation of H2O. 相似文献
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Dr. Mari Toyama Takako Takizawa Itaru Morita Prof. Noriharu Nagao Dr. Yusuke Kuramochi Prof. Hitoshi Ishida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(72):16582-16590
Two isomers of heteroleptic bis(bidentate) ruthenium(II) complexes with dimethyl sulfoxide (dmso) and chloride ligands, trans(Cl,Nbpy)- and trans(Cl,NHdpa)-[Ru(bpy)Cl(dmso-S)(Hdpa)]+ (bpy: 2,2′-bipyridine; Hdpa: di-2-pyridylamine), are synthesized. This is the first report on the selective synthesis of a pair of isomers of cis-[Ru(L)(L′)XY]n+ (L≠L′: bidentate ligands; X≠Y: monodentate ligands). The structures of the ruthenium(II) complexes are clarified by means of X-ray crystallography, and the signals in the 1H NMR spectra are assigned based on 1H–1H COSY spectra. The colors of the two isomers are clearly different in both the solid state and solution: the trans(Cl,Nbpy) isomer has a deep red color, whereas the trans(Cl,NHdpa) isomer is yellow. Although both complexes have intense absorption bands at λ≈440–450 nm, only the trans(Cl,Nbpy) isomer has a shoulder band at λ≈550 nm. DFT calculations indicate that the LUMOs of both isomers are the π* orbitals in the bpy ligand, and that the LUMO level of the trans(Cl,Nbpy) isomer is lower than that of the trans(Cl,NHdpa) isomer due to the trans effect of the Cl ligand; thus resulting in the appearance of the shoulder band. The HOMO levels are almost the same in both isomers. The energy levels are experimentally supported by cyclic voltammograms, in which these isomers have different reduction potentials and similar oxidation potentials. 相似文献
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Yong‐Min Lee Dr. Sunder N. Dhuri Dr. Sarvesh C. Sawant Dr. Jaeheung Cho Dr. Minoru Kubo Dr. Takashi Ogura Prof. Dr. Shunichi Fukuzumi Prof. Dr. Wonwoo Nam Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1803-1806
Give me an “O”! Mononuclear nonheme iron(IV) oxo complexes have been generated using water as an oxygen source and cerium(IV) as an oxidant. The high‐yield oxygenation of organic substrates in this system (see picture, Fe green, O red, N blue, C gray) is catalyzed by iron(II) complexes. The source of oxygen in the iron(IV) oxo complexes and the oxygenated products has been assigned unambiguously by isotopic labeling experiments.
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Dr. David J. Liptrot Dr. Jing‐Dong Guo Prof. Shigeru Nagase Prof. Philip P. Power 《Angewandte Chemie (International ed. in English)》2016,55(47):14766-14769
The transition metal tetra‐ and trinorbornyl bromide complexes, M(nor)4 (M=Fe, Co, Ni) and Ni(nor)3Br (nor=1‐bicyclo[2.2.1]hept‐1‐yl) and their homolytic fragmentations were studied computationally using hybrid density functional theory (DFT) at the B3PW91 and B3PW91‐D3 dispersion‐corrected levels. Experimental structures were well replicated; the dispersion correction resulted in shortened M?C bond lengths for the stable complexes, and it was found that Fe(nor)4 receives a remarkable 45.9 kcal mol?1 stabilization from the dispersion effects whereas the tetragonalized Co(nor)4 shows stabilization of 38.3 kcal mol?1. Ni(nor)4 was calculated to be highly tetragonalized with long Ni?C bonds, providing a rationale for its current synthetic inaccessibility. Isodesmic exchange evaluation for Fe(nor)4 confirmed that dispersion force attraction between norbornyl substituents is fundamental to the stability of these species. 相似文献
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Benjamin Schwarz Dr. Johannes Forster McKenna K. Goetz Duygu Yücel Claudia Berger Prof. Dr. Timo Jacob Prof. Dr. Carsten Streb 《Angewandte Chemie (International ed. in English)》2016,55(21):6329-6333
Photosynthetic water oxidation in plants occurs at an inorganic calcium manganese oxo cluster, which is known as the oxygen evolving complex (OEC), in photosystem II. Herein, we report a synthetic OEC model based on a molecular manganese vanadium oxide cluster, [Mn4V4O17(OAc)3]3?. The compound is based on a [Mn4O4]6+ cubane core, which catalyzes the homogeneous, visible‐light‐driven oxidation of water to molecular oxygen and is stabilized by a tripodal [V4O13]6? polyoxovanadate and three acetate ligands. When combined with the photosensitizer [Ru(bpy)3]2+ and the oxidant persulfate, visible‐light‐driven water oxidation with turnover numbers of approximately 1150 and turnover frequencies of about 1.75 s?1 is observed. Electrochemical, mass‐spectrometric, and spectroscopic studies provide insight into the cluster stability and reactivity. This compound could serve as a model for the molecular structure and reactivity of the OEC and for heterogeneous metal oxide water‐oxidation catalysts. 相似文献
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Prof. Dr. Shunichi Fukuzumi Takuya Mizuno Tetsuya Ojiri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(49):15794-15804
Manganese(V)–oxo–porphyrins are produced by the electron‐transfer oxidation of manganese–porphyrins with tris(2,2′‐bipyridine)ruthenium(III) ([Ru(bpy)3]3+; 2 equiv) in acetonitrile (CH3CN) containing water. The rate constants of the electron‐transfer oxidation of manganese–porphyrins have been determined and evaluated in light of the Marcus theory of electron transfer. Addition of [Ru(bpy)3]3+ to a solution of olefins (styrene and cyclohexene) in CH3CN containing water in the presence of a catalytic amount of manganese–porphyrins afforded epoxides, diols, and aldehydes efficiently. Epoxides were converted to the corresponding diols by hydrolysis, and were further oxidized to the corresponding aldehydes. The turnover numbers vary significantly depending on the type of manganese–porphyrin used owing to the difference in their oxidation potentials and the steric bulkiness of the ligand. Ethylbenzene was also oxidized to 1‐phenylethanol using manganese–porphyrins as electron‐transfer catalysts. The oxygen source in the substrate oxygenation was confirmed to be water by using 18O‐labeled water. The rate constant of the reaction of the manganese(V)–oxo species with cyclohexene was determined directly under single‐turnover conditions by monitoring the increase in absorbance attributable to the manganese(III) species produced in the reaction with cyclohexene. It has been shown that the rate‐determining step in the catalytic electron‐transfer oxygenation of cyclohexene is electron transfer from [Ru(bpy)3]3+ to the manganese–porphyrins. 相似文献
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The essential participation of agostic interactions in C−H bond activation, cyclometallation and other catalytic processes has been widely observed. To quantitatively evaluate the Mo−H−C agostic interaction in the Mo β/γ- agostomers [CpMo(CO)2(PiPr3)]+ ( Mo , 1 and Mo , 2 ) and the Mn−H−C agostic interaction in the Mn α/ϵ-agostomers [(C6H9]Mo(CO)3] ( Mn , 1 and Mn , 2 ), the comprehensive density functional theory (DFT) theoretical investigations were performed. Results indicated that the Mo β-agostomer 1 is only favorable by 0.5 kcal mol−1 than Mo γ-agostomer 2 , and the Gibbs barrier for their interconversion was 9.1 kcal mol−1. A slightly higher Gibbs barrier of 12.7 kcal mol−1 for the isomerization between the Mn α/ϵ-agostomers was also obtained. The relatively strong agostic interactions in Mo β-agostomer 1 and Mn α-agostomer 1 were further verified by the AIM (Atoms-In-Molecules) analyses and the NAdOs (natural adaptive orbitals) analyses. The findings on the agostic interaction presented in this study are believed to benefit the understandings of the agostic interaction involved catalytic processes and to promote the development of new organometallic complexes. 相似文献
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Inside Cover: Photocatalytic Water Oxidation by a Mixed‐Valent MnIII3MnIVO3 Manganese Oxo Core that Mimics the Natural Oxygen‐Evolving Center (Angew. Chem. Int. Ed. 42/2014) 下载免费PDF全文
Dr. Rami Al‐Oweini Dr. Andrea Sartorel Dr. Bassem S. Bassil Dr. Mirco Natali Dr. Serena Berardi Prof. Franco Scandola Prof. Ulrich Kortz Prof. Marcella Bonchio 《Angewandte Chemie (International ed. in English)》2014,53(42):11100-11100
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Dr. Amanda G. Jarvis Dr. Petr E. Sehnal Dr. Somia E. Bajwa Dr. Adrian C. Whitwood Dr. Xiangbiao Zhang Man Sing Cheung Prof. Dr. Zhenyang Lin Prof. Dr. Ian J. S. Fairlamb 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(19):6034-6043
A multidentate and flexible diolefin–diphosphine ligand, based on the dibenzylidene acetone core, namely dbaphos ( 1 ), is reported herein. The ligand adopts an array of different geometries at Pt, Pd and Rh. At PtII the dbaphos ligand forms cis‐ and trans‐diphosphine complexes and can be defined as a wide‐angle spanning ligand. 1H NMR spectroscopic analysis shows that the β‐hydrogen of one olefin moiety interacts with the PtII centre (an anagostic interaction), which is supported by DFT calculations. At Pd0 and RhI, the dbaphos ligand exhibits both olefin and phosphine interactions with the metal centres. The Pd0 complex of dbaphos is dinuclear, with bridging diphosphines. The complex exhibits the coordination of one olefin moiety, which is in dynamic exchange (intramolecular) with the other “free” olefin. The Pd0 complex of dbaphos reacts with iodobenzene to afford trans‐[PdII(dbaphos)I(Ph)]. In the case of RhI, dbaphos coordinates to form a structure in which the phosphine and olefin moieties occupy both axial and equatorial sites, which stands in contrast to a related bidentate olefin, phosphine ligand (“Lei” ligand), in which the olefins occupy the equatorial sites and phosphines the axial sites, exclusively. 相似文献
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C−N Bond Formation from a Masked High‐Valent Copper Complex Stabilized by Redox Non‐Innocent Ligands 下载免费PDF全文
Jérémy Jacquet Pauline Chaumont Geoffrey Gontard Dr. Maylis Orio Dr. Hervé Vezin Dr. Sébastien Blanchard Dr. Marine Desage‐El Murr Prof. Louis Fensterbank 《Angewandte Chemie (International ed. in English)》2016,55(36):10712-10716
The reactivity of a stable copper(II) complex bearing fully oxidized iminobenzoquinone redox ligands towards nucleophiles is described. In sharp contrast with its genuine low‐valent counterpart bearing reduced ligands, this complex performs high‐yielding C?N bond formations. Mechanistic studies suggest that this behavior could stem from a mechanism akin to reductive elimination occurring at the metal center but facilitated by the ligand: it is proposed that a masked high oxidation state of the metal can be stabilized as a lower copper(II) oxidation state by the redox ligands without forfeiting its ability to behave as a high‐valent copper(III) center. These observations are substantiated by a combination of advanced EPR spectroscopy techniques with DFT studies. This work sheds light on the potential of redox ligands as promoters of unusual reactivities at metal centers and illustrates the concept of masked high‐valent metallic species. 相似文献