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Cyclometalated Mono‐ and Dinuclear IrIII Complexes with “Click”‐Derived Triazoles and Mesoionic Carbenes
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Dr. Ramananda Maity Stephan Hohloch Prof. Dr. Cheng‐Yong Su Margarethe van der Meer Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9952-9961
Orthometalation at IrIII centers is usually facile, and such orthometalated complexes often display intriguing electronic and catalytic properties. By using a central phenyl ring as C?H activation sites, we present here mono‐ and dinuclear IrIII complexes with “click”‐derived 1,2,3‐triazole and 1,2,3‐triazol‐5‐ylidene ligands, in which the wingtip phenyl groups in the aforementioned ligands are additionally orthometalated and bind as carbanionic donors to the IrIII centers. Structural characterization of the complexes reveal a piano stool‐type of coordination around the metal centers with the “click”‐derived ligands bound either with C^N or C^C donor sets to the IrIII centers. Furthermore, whereas bond localization is observed within the 1,2,3‐triazole ligands, a more delocalized situation is found in their 1,2,3‐triazol‐5‐ylidene counterparts. All complexes were subjected to catalytic tests for the transfer hydrogenation of benzaldehyde and acetophenone. The dinuclear complexes turned out to be more active than their mononuclear counterparts. We present here the first examples of stable, isomer‐pure, dinuclear cyclometalated IrIII complexes with poly‐mesoionic‐carbene ligands. 相似文献
3.
Bernd Wrackmeyer 《Angewandte Chemie (International ed. in English)》1999,38(6):771-772
More and more metal complexes with terminal borylene ligands will be synthesized. Although these ligands in metal complexes must be stabilized either by integration of the boron atom into a polyhedral skeleton ( 1 ) or by B–N π interactions with a bulky amino group ( 2 ), the route to new complexes with terminal RB ligands (R=alkyl, aryl) is clearly indicated. 相似文献
4.
Uwe Schmidt Luis Werner Merle Arrowsmith Andrea Deissenberger Alexander Hermann Alexander Hofmann Stefan Ullrich James D. Mattock Alfredo Vargas Holger Braunschweig 《Angewandte Chemie (International ed. in English)》2020,59(1):325-329
The reaction of aryl‐ and amino(dihydro)boranes with dibora[2]ferrocenophane 1 leads to the formation 1,3‐trans‐dihydrotriboranes by formal hydrogenation and insertion of a borylene unit into the B=B bond. The aryltriborane derivatives undergo reversible photoisomerization to the cis‐1,2‐μ‐H‐3‐hydrotriboranes, while hydride abstraction affords cationic triboranes, which represent the first doubly base‐stabilized B3H4+ analogues. 相似文献
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Kathrin Götz Martin Kaupp Prof. Dr. Holger Braunschweig Prof. Dr. Dietmar Stalke Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):623-632
Bonding in borylene‐, carbene‐, and vinylidene‐bridged dinuclear manganese complexes [MnCp(CO)2]2X (X=B‐tBu, B=NMe2, CH2, C?CH2) has been compared by analyses based on quantum theory of atoms in molecules (QTAIM), on the electron‐localization function (ELF), and by natural‐population analyses. All of the density functional theory based analyses agree on the absence of a significant direct Mn? Mn bond in these complexes and confirm a dominance of delocalized bonding via the bridging ligand. Interestingly, however, the topology of both charge density and ELF related to the Mn‐bridge‐Mn bonding depend qualitatively on the chosen density functional (except for the methylene‐bridged complex, which exhibits only one three‐center‐bonding attractor both in ??2ρ and in ELF). While gradient‐corrected functionals provide a picture with localized two‐center X? Mn bonding, increasing exact‐exchange admixture in hybrid functionals concentrates charge below the bridging atom and suggests a three‐center bonding situation. For example, the bridging boron ligands may be described either as substituted boranes (e.g., at BLYP or BP86 levels) or as true bridging borylenes (e.g., at BHLYP level). This dependence on the theoretical level appears to derive from a bifurcation between two different bonding situations and is discussed in terms of charge transfer between X and Mn, and in the context of self‐interaction errors exhibited by popular functionals. 相似文献
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Dudekula Sharmila Bijan Mondal Rongala Ramalakshmi Sangita Kundu Dr. Babu Varghese Prof. Sundargopal Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):5074-5083
A combined experimental and quantum chemical study of Group 7 borane, trimetallic triply bridged borylene and boride complexes has been undertaken. Treatment of [{Cp*CoCl}2] (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with LiBH4 ? thf at ?78 °C, followed by room‐temperature reaction with three equivalents of [Mn2(CO)10] yielded a manganese hexahydridodiborate compound [{(OC)4Mn}(η6‐B2H6){Mn(CO)3}2(μ‐H)] ( 1 ) and a triply bridged borylene complex [(μ3‐BH)(Cp*Co)2(μ‐CO)(μ‐H)2MnH(CO)3] ( 2 ). In a similar fashion, [Re2(CO)10] generated [(μ3‐BH)(Cp*Co)2(μ‐CO)(μ‐H)2ReH(CO)3] ( 3 ) and [(μ3‐BH)(Cp*Co)2(μ‐CO)2(μ‐H)Co(CO)3] ( 4 ) in modest yields. In contrast, [Ru3(CO)12] under similar reaction conditions yielded a heterometallic semi‐interstitial boride cluster [(Cp*Co)(μ‐H)3Ru3(CO)9B] ( 5 ). The solid‐state X‐ray structure of compound 1 shows a significantly shorter boron–boron bond length. The detailed spectroscopic data of 1 and the unusual structural and bonding features have been described. All the complexes have been characterized by using 1H, 11B, 13C NMR spectroscopy, mass spectrometry, and X‐ray diffraction analysis. The DFT computations were used to shed light on the bonding and electronic structures of these new compounds. The study reveals a dominant B?H?Mn, a weak B?B?Mn interaction, and an enhanced B?B bonding in 1 . 相似文献
7.
Construction of Pendant‐Armed Schiff‐Base Macrocyclic Dinuclear Zinc Complexes and Their Selective Recognition of Acetate Ions
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Two new flexible extended dialdehydes (H2hpdd and H2pdd) with different functional pendant arms (? CH2CH2PhOH and ? CH2CH2Ph) have been synthesized and reacted with 1,2‐bis(2‐aminoethoxy)ethane to prepare Schiff‐base macrocyclic complexes in the presence of a ZnII‐ion template. As a result, two preorganized dinuclear ZnII intermediates ( 1 and 2 ), as well as two 42‐membered folded [2+2] macrocyclic dinuclear ZnII complexes ( 3 and 4 ), were produced. The central zinc ions in compounds 1 – 4 showed distinguishable coordination patterns with the dialdehydes and the [2+2] macrocyclic ligands, in which a subtle pH‐adjustment function of the two pendant arms (with or without the phenolic hydroxy group) was believed to play a vital role. Furthermore, cation‐ and anion‐recognition experiments for complexes 3 and 4 revealed that they could selectively recognize acetate ions by the formation of 1:1 stoichiometric complexes, as verified by changes in their UV/Vis and MS (ESI) spectra and even by the naked eye. 相似文献
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Ranjit Bag Sourav Kar Suvam Saha Suman Gomosta Beesam Raghavendra Thierry Roisnel Sundargopal Ghosh 《化学:亚洲杂志》2020,15(6):780-786
Triply‐bridging bis‐{hydrido(borylene)} and bis‐borylene species of groups 6, 8 and 9 transition metals are reported. Mild thermolysis of [Fe2(CO)9] with an in situ produced intermediate, generated from the low‐temperature reaction of [Cp*WCl4] (Cp*=η5‐C5Me5) and [LiBH4?THF] afforded triply‐bridging bis‐{hydrido(borylene)}, [(μ3‐BH)2H2{Cp*W(CO)2}2{Fe(CO)2}] ( 1 ) and bis‐borylene, [(μ3‐BH)2{Cp*W(CO)2}2{Fe(CO)3}] ( 2 ). The chemical bonding analyses of 1 show that the B?H interactions in bis‐{hydrido (borylene)} species is stronger as compared to the M?H ones. Frontier molecular orbital analysis shows a significantly larger energy gap between the HOMO‐LUMO for 2 as compared to 1 . In an attempt to synthesize the ruthenium analogue of 1 , a similar reaction has been performed with [Ru3(CO)12]. Although we failed to get the bis‐{hydrido(borylene)} species, the reaction afforded triply‐bridging bis‐borylene species [(μ3‐BH)2{WCp*(CO)2}2{Ru(CO)3}] ( 2′ ), an analogue of 2 . In search for the isolation of bridging bis‐borylene species of Rh, we have treated [Co2(CO)8] with nido‐[(RhCp*)2(B3H7)], which afforded triply‐bridging bis‐borylene species [(μ3‐BH)2(RhCp*)2Co2(CO)4(μ‐CO)] ( 3 ). All the compounds have been characterized by means of single‐crystal X‐ray diffraction study; 1H, 11B, 13C NMR spectroscopy; IR spectroscopy and mass spectrometry. 相似文献
9.
合成了一系列含N-杂环卡宾二硫化碳加合物配体的锰铼金属有机化合物,其中包括3种单核化合物和3种双核化合物,对它们的结构进行了表征,并研究其反应性和电化学性质. 与三烷基膦二硫化碳配体相比,含N-杂环卡宾二硫化碳加合物配体的锰铼金属有机化合物展现出不同的反应特性. 研究结果表明,[MnRe(CO)6(μ-H){μ-CH3SC(S)IMes2}]配合物具有催化质子还原成氢气的能力. 相似文献
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Two transition metal dinuclear complexes of [Mn2(OOCC6H4SSC6H4COO)- (Phen)2(H20)]n 1 and [CuE(OOCC6H4S)2(Phen)2] 2 were hydrothermally synthesized by the reaction of equivalent metal dichloride with 2,2'-dithiobis(benzoic acid) (HE-DTBB). Structure analysis indicates that each Mn2+ ion in I is coordinated by one chelate phen ligand, one bridging water molecule and three DTBB ligands forming Mn2+ dinuclear units which are further linked into one-dimensional chain by DTBB ligand. Under similar reaction conditions, the 2,2'-dithio- his(benzoic acid) ligand undergoes thiol reduction to form 2-mercaptobenzoic (H-2-MBA) in 2 where two Cu2+ ions are coordinated by phen and MBA ligands only constructing a dinuclear unit. 相似文献
11.
Copper(II) and Zinc(II) Complexes of Conformationally Constrained Polyazamacrocycles as Efficient Catalysts for RNA Model Substrate Cleavage in Aqueous Solution at Physiological pH
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Daniel Bím Dr. Eva Svobodová Václav Eigner Dr. Lubomír Rulíšek Prof. Jana Hodačová 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10426-10437
As part of a quest for efficient artificial catalysts of RNA phosphodiester bond cleavage, conformationally constrained mono‐ and bis‐polyazamacrocycles in which tri‐ or tetraazaalkane chains link the ortho positions of a benzene ring were synthesized. The catalytic activities of mono‐ and dinuclear copper(II) and zinc(II) complexes of these polyazamacrocycles towards cleavage of the P?O bond in 2‐hydroxypropyl‐4‐nitrophenylphosphate (HPNP) in aqueous solution at pH 7 have been determined. Only the complexes of the ligands incorporating three nitrogen atoms in a macrocycle proved to be capable of efficiently catalyzing HPNP transesterification. The dinuclear complexes were found to be approximately twice as efficient as their mononuclear counterparts, and exhibited Michaelis–Menten saturation kinetics with calculated rate constants of kcat≈10?4 s?1. By means of quantum chemical calculations (DFT/COSMO‐RS), several plausible reaction coordinates were described. By correlating the calculated barriers with the experimental kinetic data, two possible reaction scenarios were revealed, with activation free energies of 20–25 kcal mol?1. 相似文献
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Holger Braunschweig Prof. Dr. Melanie Forster Fabian Seeler Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(2):469-473
Herein we report on the synthesis and structural characterization of a representative range of novel heterodinuclear bridging rhodium and iridium borylene complexes. The iridium borylene complexes feature an unusual coordination mode of the borylene ligand. Furthermore, the first instance of a heterodinuclear‐bridged borylene compound containing a chromium atom in the three‐membered ring is reported. 相似文献
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The synthesis and characterisation of the dinuclear iron complex [(eta 5-C5H5)Fe(CO)2]2B(2,4,6-Me3C6H2) containing an unsupported bridging borylene ligand are reported. 相似文献
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Philipp Bissinger Prof. Dr. Holger Braunschweig Dr. Alexander Damme Dr. Rian D. Dewhurst Dr. Katharina Kraft Thomas Kramer Dr. Krzysztof Radacki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13402-13407
The synthesis of base‐stabilized boryl and borylene complexes is reported. An N‐heterocyclic carbene (NHC)‐stabilized iron–dihydroboryl complex was prepared by two different routes including methane liberation and salt elimination. A range of base‐stabilized iron–dichloroboryl complexes was prepared by addition of Lewis bases to boryl complexes. Base‐stabilized, cationic monochloroborylene complexes were synthesized from these boryl complexes by halide abstraction by using weakly coordinating anions. 相似文献
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Bruno Pribanic Monica Trincado Frederik Eiler Matthias Vogt Aleix Comas‐Vives Hansjrg Grützmacher 《Angewandte Chemie (International ed. in English)》2020,59(36):15603-15609
The dehydrogenation of organosilanes (RxSiH4?x) under the formation of Si?Si bonds is an intensively investigated process leading to oligo‐ or polysilanes. The reverse reaction is little studied. To date, the hydrogenolysis of Si?Si bonds requires very harsh conditions and is very unselective, leading to multiple side products. Herein, we describe a new catalytic hydrogenation of oligo‐ and polysilanes that is highly selective and proceeds under mild conditions. New low‐valent nickel hydride complexes are used as catalysts and secondary silanes, RR′SiH2, are obtained as products in high purity. 相似文献
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Three‐Way Cooperativity in d8 Metal Complexes with Ligands Displaying Chemical and Redox Non‐Innocence
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Dr. Naina Deibel Stephan Hohloch Dr. David Schweinfurth Fritz Weisser Dr. Anita Grupp Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15178-15187
Reversible proton‐ and electron‐transfer steps are crucial for various chemical transformations. The electron‐reservoir behavior of redox non‐innocent ligands and the proton‐reservoir behavior of chemically non‐innocent ligands can be cooperatively utilized for substrate bond activation. Although site‐decoupled proton‐ and electron‐transfer steps are often found in enzymatic systems, generating model metal complexes with these properties remains challenging. To tackle this issue, we present herein complexes [(cod?H)M(μ‐L2?) M (cod?H)] (M=PtII, [ 1 ] or PdII, [ 2 ], cod=1,5‐cyclooctadiene, H2L=2,5‐di‐[2,6‐(diisopropyl)anilino]‐1,4‐benzoquinone), in which cod acts as a proton reservoir, and L2? as an electron reservoir. Protonation of [ 2 ] leads to an unusual tetranuclear complex. However, [ 1 ] can be stepwise reversibly protonated with up to two protons on the cod?H ligands, and the protonated forms can be stepwise reversibly reduced with up to two electrons on the L2? ligand. The doubly protonated form of [ 1 ] is also shown to react with OMe? leading to an activation of the cod ligands. The site‐decoupled proton and electron reservoir sources work in tandem in a three‐way cooperative process that results in the transfer of two electrons and two protons to a substrate leading to its double reduction and protonation. These results will possibly provide new insights into developing catalysts for multiple proton‐ and electron‐transfer reactions by using metal complexes of non‐innocent ligands. 相似文献
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The synthesis and coordination properties of mixed N,O‐compartmental ligands is described. Macrocyclic ligands 8 and 15 were designed to mimic transition‐state analogs for the production of catalytic antibodies for C−H activation reactions. Reaction of 8 with vanadyl cations yields the dinuclear complex 9 , which was characterized by X‐ray crystallography. Amputated ligands 17 and 18 react with various transition‐metal cations to yield complexes designed to act as coenzymes for the catalytic antibodies. The Ni complex of 17 ( 19 ) was also structurally characterized by X‐ray crystallography. 相似文献
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M. Sc. Małgorzata Krasowska Prof. Dr. Holger F. Bettinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12858-12863
The addition of borylenes (RB) to prototypical carbon?carbon multiple bonds (ethyne, ethene) and the insertion into a C?H bond of methane involves weakly bound van der Waals complexes of the reaction partners according to computational chemistry methods. Geometries of all complexes were optimized using spin‐component scaled second‐order Møller–Plesset perturbation theory (SCS‐MP2) in combination with a quadruple‐ζ (def2‐QZVP) basis set. Energies were further refined using the coupled‐cluster (CCSD(T)) method in combination with basis sets up to quadruple‐ζ quality (def2‐QZVP and aug‐cc‐pVTZ). All of the complexes of borylenes studied correspond to shallow minima on their potential‐energy surfaces. Borylene complexes with ethyne are the most stable and those with methane are the least stable ones. Aminoborylene complexes BNHR with ethyne and ethene are stabilized mainly by NH ??? π interactions. Symmetry‐adapted perturbation theory (SAPT) was performed to analyze the nature of the interaction between borylene molecules and hydrocarbons. Most of the ethyne complexes are dominated by electrostatic interactions, whereas for most of the ethene and all of the methane complexes the interaction is mainly dispersive. 相似文献
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DFT/B3LYP calculations are able to reproduce the magnetic behaviour of dinuclear complexes of CuII within the framework of the Heisenberg Hamiltonian. The trinuclear complexes recently characterized by Glaser et al from trinucleating Robson‐type ligands provide an opportunity to extend the application of the broken symmetry formalism to a nonsymmetric CuIICuIICuII framework. At variance with the tentative fit deduced from experiment, the calculations suggest that the coupling along the three magnetic centers could be weak. 相似文献