Prof. Dr. Christian Limberg

Profil

• Aktivierung kleiner Moleküle in Abhängigkeit vom Abstand zweier funktionaler Zentren

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  Förderer: Einstein Zentrum Zeitraum: 02/2019 - 12/2025 Projektleitung: Prof. Dr. Christian Limberg

• Chemische Analysen

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  Zeitraum: 02/2014 - 02/2024 Projektleitung: Prof. Dr. Christian Limberg

• Cluster: Integrale Konzepte der Katalyse II(D1.2,D2.3/D2.5,D3.1/D3.4)

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  Förderer: DFG Exzellenzinitiative Cluster Zeitraum: 11/2012 - 10/2017 Projektleitung: Prof. Dr. Christian Limberg

• Cluster: Integrale Konzepte der Katalyse (Teilbereich A 5)

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  Förderer: DFG Exzellenzinitiative Cluster Zeitraum: 11/2007 - 10/2012 Projektleitung: Prof. Dr. Christian Limberg

• DFG-Sachbeihilfe: Molekulare Metallsiloxid-Verbindungen als Modelle für funktionale Einheiten oxidischer Gerüste und Oberflächen

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  Förderer: DFG Sachbeihilfe Zeitraum: 01/2021 - 12/2026 Projektleitung: Prof. Dr. Christian Limberg

• Die Aufdeckung des photo-induzierten Assemblierungsmechanismus des lichtgetriebenen Wasseroxidationskomplexes in Photosystem II

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  Förderer: DFG Exzellenzinitiative Cluster Zeitraum: 11/2017 - 12/2018 Projektleitung: Prof. Dr. Athina Zouni

• Die Bismutmolybdat-vermittelte Propenoxidation - Modellierung reaktiver Intermediate und Synthese von Komplexen mit neuartigen Oxometall-Strukturelementen

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  Förderer: DFG Sachbeihilfe Zeitraum: 03/2003 - 12/2007 Projektleitung: Prof. Dr. Christian Limberg

• EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

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  Förderer: DFG Exzellenzstrategie Cluster Zeitraum: 01/2019 - 12/2022 Projektleitung: Prof. Dr. Athina Zouni

• Heterometallische Molybdän/p-Block-Verbindungen: Komplexe mit neuartigen Bindungssituationen, Modelle für Oberflächenspezies und Einkomponenten-Vorstufen für funktionale Materialien

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  Förderer: DFG Sachbeihilfe Zeitraum: 06/2007 - 02/2012 Projektleitung: Prof. Dr. Christian Limberg

• Homogene und heterogene Oxidationsreaktionen mit Molybdänoxo-Verbindungen - Modellierung von Intermediaten und Synthese von Komplexen mit neuartigen Oxometall-Strukturelementen

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  Förderer: DFG Sachbeihilfe Zeitraum: 02/2004 - 02/2005 Projektleitung: Prof. Dr. Christian Limberg

• Kooperation Metalloxid/Wasser-Systeme im SFB 1109

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  Förderer: Max-Planck-Gesellschaft Zeitraum: 11/2017 - 09/2021 Projektleitung: Prof. Dr. Christian Limberg

• Metall-Kooperation bei der Disauerstoff-Aktivierung in molekularen Siloxid-Komplexen

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  Förderer: DFG Sachbeihilfe Zeitraum: 01/2018 - 06/2022 Projektleitung: Prof. Dr. Christian Limberg

• Neue starre Calixaren-basierte Liganden für die Katalyse und Biomimetik

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  Förderer: German-Israeli Foundation Zeitraum: 01/2013 - 12/2016 Projektleitung: Prof. Dr. Christian Limberg

• SFB 1109/1: Molekulare Einblicke in Metalloxid-Wasser-Systeme: Strukturelle Evolution, Grenzflächen und Auflösung

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  Förderer: DFG Sonderforschungsbereich Zeitraum: 04/2014 - 12/2017 Projektleitung: Prof. Dr. Christian Limberg

• SFB 1109/1: Oxo-Gerüste in molekularen Verbindungen: Modellierung von Frühstadien, maßgeschneierte Strukturmotive für neuartige Materialien und Wasserreaktivität (TP A04)

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  Förderer: DFG Sonderforschungsbereich Zeitraum: 04/2014 - 12/2017 Projektleitung: Prof. Dr. Christian Limberg

• SFB 1109/2: Oxo-Gerüste in molekularen Verbindungen: Modellierung von Frühstadien, maßgeschneierte Strukturmotive für neuartige Materialien und Wasserreaktivität (TP A 04)

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  Förderer: DFG Sonderforschungsbereich Zeitraum: 01/2018 - 12/2018 Projektleitung: Prof. Dr. Christian Limberg

• SFB 1349/1: Kooperierende Lewis-Paare auf Basis von Fluor-haltigen Bismut- und Aluminium- Akzeptoreinheiten (TP B01)

  Quelle ↗

  Förderer: DFG Sonderforschungsbereich Zeitraum: 01/2019 - 12/2022 Projektleitung: Prof. Dr. Christian Limberg

• SFB 546 II-III: Synthese und Reaktivität von Molekülmodellen für die aktiven Stellen Vanadiumoxid-basierender Katalysatoren (Teilprojekt B 5)

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  Förderer: DFG Sonderforschungsbereich Zeitraum: 08/2003 - 06/2011 Projektleitung: Prof. Dr. Christian Limberg

• Übergangsmetallkomplexe mit Lewis-sauren Bismut-Zentren im Rückgrat ambiphiler Liganden"

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  Förderer: DFG Sachbeihilfe Zeitraum: 09/2012 - 12/2016 Projektleitung: Prof. Dr. Christian Limberg

• Übergangsmetall-Komplexe und ihre oxidierende Wirkung

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  Zeitraum: 01/2006 - 12/2015 Projektleitung: Prof. Dr. Christian Limberg

• Science & Startups Berlin

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  19 Treffer56.7%
  • Zuwendung im Rahmen des Programms „exist – Existenzgründungen aus der Wissenschaft“ aus dem Bundeshaushalt, Einzelplan 09, Kapitel 02, Titel 68607, Haushaltsjahr 2026, sowie aus Mitteln des Europäischen Strukturfonds (hier Euro-päischer Sozialfonds Plus – ESF Plus) Förderperiode 2021-2027 – Kofinanzierung für das Vorhaben: „exist Women“
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• A.P.E. Research srl

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  269 Treffer56.0%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
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    56.0%
  • Integrated Self-Assembled SWITCHable Systems and Materials: Towards Responsive Organic Electronics – A Multi-Site Innovative Training Action (iSwitch)
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    53.2%

• International Business Machines Corporation Research GmbH

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  203 Treffer56.0%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
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    56.0%
  • EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
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    54.2%

• Graphenea S.A.

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  133 Treffer56.0%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
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    56.0%

• Istituto Italiano di Tecnologia

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  133 Treffer56.0%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
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    56.0%

• Peugeot Citroen Automobiles S.A.

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  129 Treffer55.0%
  • EU: Monomer Sequence Control in Polymers: Toward Next-Generation Precision Materials (EURO-SEQUENCES)
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    55.0%

• Ionera Technologies GmbH

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  127 Treffer55.0%
  • EU: Monomer Sequence Control in Polymers: Toward Next-Generation Precision Materials (EURO-SEQUENCES)
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    55.0%

• Magwel NV

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  67 Treffer54.2%
  • EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
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    54.2%

• NVIDIA GmbH

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  67 Treffer54.2%
  • EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
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    54.2%

• Bernstein Center for Computational Neuroscience Berlin

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  127 Treffer53.8%
  • DFG-Sachbeihilfe: Aufmerksamkeit und sensorische Integration im aktiven Sehen von bewegten Objekten
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    53.8%
  • SFB 1315/2: Mechanismen und Störungen der Gedächtniskonsolidierung: Von Synapsen zur Systemebene
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    49.5%

• The Mechanism of Water Oxidation: From Electrolysis via Homogeneous to Biological Catalysis

  2010

  ChemCatChem · 1747 Zitationen · DOI

  Abstract Striving for new solar fuels, the water oxidation reaction currently is considered to be a bottleneck, hampering progress in the development of applicable technologies for the conversion of light into storable fuels. This review compares and unifies viewpoints on water oxidation from various fields of catalysis research. The first part deals with the thermodynamic efficiency and mechanisms of electrochemical water splitting by metal oxides on electrode surfaces, explaining the recent concept of the potential‐determining step. Subsequently, novel cobalt oxide‐based catalysts for heterogeneous (electro)catalysis are discussed. These may share structural and functional properties with surface oxides, multinuclear molecular catalysts and the catalytic manganese–calcium complex of photosynthetic water oxidation. Recent developments in homogeneous water‐oxidation catalysis are outlined with a focus on the discovery of mononuclear ruthenium (and non‐ruthenium) complexes that efficiently mediate O 2 evolution from water. Water oxidation in photosynthesis is the subject of a concise presentation of structure and function of the natural paragon—the manganese–calcium complex in photosystem II—for which ideas concerning redox‐potential leveling, proton removal, and OO bond formation mechanisms are discussed. The last part highlights common themes and unifying concepts.

• Multifunctional “Clickates” as Versatile Extended Heteroaromatic Building Blocks: Efficient Synthesis via Click Chemistry, Conformational Preferences, and Metal Coordination

  2007

  Chemistry - A European Journal · 248 Zitationen · DOI

  Click chemistry has been utilized to access 2,6-bis(1-aryl-1,2,3-triazol-4-yl)pyridines (BTPs) as versatile extended heteroaromatic building blocks for their exploitation in supramolecular chemistry, in particular foldamer and ligand design. In addition to their high-yielding synthesis using Cu(I)-catalyzed Huisgen-type 1,3-dipolar cycloaddition reactions the formed triazole moieties constitute an integral part of the BTP framework and encode both its pronounced conformational preferences as well as its chelating ability. A diverse set of symmetrical and non-symmetrical BTPs carrying electron-donating and -withdrawing substituents at both terminal aryl and the central pyridine moieties has efficiently been synthesized and could furthermore readily be postfunctionalized with amphiphilic side chains and porphyrin chromophores. In both solution and solid state, the BTP scaffold adopts a highly conserved horseshoe-like anti-anti conformation. Upon protonation or metal coordination, the BTP scaffold switches to the chelating syn-syn conformation. Iron and europium complexes have been prepared, successfully characterized by single-crystal X-ray diffraction analysis, and investigated with regard to their spin state and luminescent properties. The extended heteroaromatic BTP scaffold should prove useful for the design of responsive foldamer backbones and the preparation of new magnetic and emissive materials.

• The Role of Radicals in Metal‐Assisted Oxygenation Reactions

  2003

  Angewandte Chemie International Edition · 186 Zitationen · DOI

  The oxo-functionalization of organic substrates with the aid of metal oxo moieties is of fundamental importance not only in nature but also in academic and industrial research. Nevertheless the corresponding reaction mechanisms remain among the most enigmatic in chemistry and few of them are understood in detail. Recent research efforts have resulted in significantly improved information: in the cases of many oxygenation reactions evidence has been provided for the occurrence radical intermediates, even though the high selectivity observed suggests to a different mechanism. Examples stem from various areas of chemistry and include processes involving molecular metal oxo complexes, gas-phase and matrix-isolated species, metalloenzymes, and solid-state oxide surfaces. This review treats this seemingly wide variety of systems with the aim of providing an overview of common reactivity patterns and principles, as well as open problems.

• A Dinuclear Nickel(I) Dinitrogen Complex and its Reduction in Single‐Electron Steps

  2009

  Angewandte Chemie International Edition · 162 Zitationen · DOI

  Electron by electron: Beta-diketiminato nickel(I) complex fragments are capable of activating N(2) through coordination. The resulting complex can be reduced in two single-electron steps, which further activates the N-N bond. The picture shows the structure of the singly reduced complex with mu-eta(1):eta(1)-bound N(2).

• Catalytic Epoxidation and 1,2‐Dihydroxylation of Olefins with Bispidine–Iron(<scp>II</scp>)/H₂O₂ Systems

  2006

  Angewandte Chemie International Edition · 151 Zitationen · DOI

  Going ferryl: FeII complexes with two isomeric bispidine ligands catalyze the oxidation of cyclooctene with H2O2 in MeCN under aerobic conditions with high selectivity for the epoxide (see scheme; L=bispidine ligand). An {FeIVO} complex is postulated to be the oxidant, formed by the homolytic cleavage of the OO bond of an {FeIII-OOH} intermediate. Performing the reaction under argon gives a mixture of cis and trans diols as well as the epoxide.

• Activation of Small Molecules at Nickel(I) Moieties

  2017

  Journal of the American Chemical Society · 106 Zitationen · DOI

  The activation and selective transformation of virtually inexhaustible or easy-to-generate chemicals like N2, O2, CO2, CO, H2, or methane gas to value-added products is a lively area of current research, because of its economic relevance as well as its huge ecological impact. Biologists and chemists have put forth a lot of effort toward understanding and modeling the mechanisms of biological small-molecule activation, and in several catalytic cycles proposed for nickel-containing enzymes, nickel(I) plays a key role. In recent years also in synthetic chemistry the huge potential of complex nickel(I) units for the activation and transformation of small molecules has been discovered and exploited. This Perspective highlights some representative examples of nickel(I)-based small-molecule activation, intending to establish awareness of the competencies and scope of nickel(I) compounds.

• Complexes of Click‐Derived Bistriazolylpyridines: Remarkable Electronic Influence of Remote Substituents on Thermodynamic Stability as well as Electronic and Magnetic Properties

  2010

  Chemistry - A European Journal · 100 Zitationen · DOI

  2,6-Bis(1,2,3-triazol-4-yl)pyridine (btp) ligands with substitution patterns ranging from strongly electron-donating to strongly electron-accepting groups, readily prepared by means of Cu-catalyzed 1,3-dipolar cycloaddition (the "click" reaction), were investigated with regard to their complexation behavior, and the properties of the resulting transition-metal compounds were compared. Metal-btp complexes of 1:1 stoichiometry, that is, [Ru(btp)Cl(2)(dmso)] and [Zn(btp)Br(2)], could be isolated and were crystallographically characterized: they display octahedral and trigonal-bipyramidal coordination geometries, respectively, and exhibit high aggregation tendencies due to efficient pi-pi stacking leading to low solubilities. Metal-btp complexes of 1:2 stoichiometry, that is, [Fe(btp)(2)](2+) and [Ru(btp)(2)](2+), could also be synthesized and their metal centers show the expected octahedral coordination spheres. The iron compounds exhibit quite a complex magnetic behavior in the solid state including spin crossover near room temperature, and hysteresis and locking into high-spin states on tempering at 400 K, depending on the substituents on the btp ligands. Cyclic voltammetry studies of [Ru(btp)(2)](2+) reveal strong modulation of the oxidation potentials by more than 0.6 V and a clear linear correlation to the Hammett constant (sigma(para)) of the substituent at the pyridine core. Isothermal titration calorimetry was used to measure the thermodynamics of the Fe(II)-btp complexation process and enabled accurate determination of the complexation enthalpies, which display a linear relationship with the sigma(para) values for the terminal phenyl substituents. Detailed NMR spectroscopic studies finally revealed that in the case of Fe(II) complexation, dynamics are rapid for all investigated btp derivatives in acetonitrile, while replacing Fe(II) by Ru(II) or changing the solvent to dichloromethane effectively slows down ligand exchange. The results nicely demonstrate the utility of substituent parameters, originally developed for linear free-energy relationships to explain reactivity in organic reactions, in coordination chemistry, and to illustrate the potential to custom-design btp ligands and complexes thereof with predictable properties. The fast equilibration of the [Fe(btp)(2)](2+) complexes together with their tunable stability and interesting magnetic properties should enable the design of dynamic metallosupramolecular materials with advantageous properties.

• Molecular Cu^II‐O‐Cu^IIComplexes: Still Waters Run Deep

  2014

  Angewandte Chemie International Edition · 97 Zitationen · DOI

  Research on O2 activation at ligated Cu(I) is fueled by its biological relevance and the quest for efficient oxidation catalysts. A rarely observed reaction is the formation of a Cu(II) -O-Cu(II) species, which is more special than it appears at first sight: a single oxo ligand between two Cu(II) centers experiences considerable electron density, and this makes the corresponding complexes reactive and difficult to access. Hence, only a small number of these compounds have been synthesized and characterized unequivocally to date, and as biological relevance was not apparent, they remained unappreciated. However, recently they moved into the spotlight, when Cu(II) -O-Cu(II) cores were proposed as the active species in the challenging oxidation of methane to methanol at the surface of a Cu-grafted zeolite and in the active center of the copper enzyme particulate methane monooxygenase. This Minireview provides an overview of these systems with a special focus on their reactivity and spectroscopic features.

• Nickel(i)-mediated transformations of carbon dioxide in closed synthetic cycles: reductive cleavage and coupling of CO2 generating NiICO, NiIICO3 and NiIIC2O4NiII entities

  2013

  Chemical Communications · 92 Zitationen · DOI

  The β-diketiminato nickel(I) complex K2[L(tBu)Ni(I)(N2(2-))Ni(I)L(tBu)] reacts with CO2 via reductive disproportionation to form CO and CO3(2-) containing products, whereas after employment of the Ni(I) precursor [L(tBu)Ni(I)(N2)Ni(I)L(tBu)] reductive coupling of CO2 was observed giving an oxalate bridged dinickel(II) complex. The addition of KC8 to the carbonate and oxalate compounds formed leads to the regeneration of the initial Ni(I) complexes in an N2 atmosphere, thus closing synthetic cycles.

• Bispidine Ligand Effects on Iron/Hydrogen Peroxide Chemistry

  2004

  Angewandte Chemie International Edition · 89 Zitationen · DOI

  . ‥and yet so different. Non-heme iron complexes catalyze the stereoselective oxidation of CH and CC bonds. Isomeric FeIII-η1-hydroperoxo and FeIII-η2-peroxo complexes (see picture), important intermediates in these reactions, were studied by EPR, resonance Raman, and UV/Vis spectroscopies.

• β-Diketiminato Nickel(I) Complexes with Very Weak Ligation Allowing for H₂ and N₂ Activation

  2009

  Organometallics · 83 Zitationen · DOI

  Reaction of [LtBuNiBr] (LtBu = [HC(C(CMe3)NC6H3(iPr)2)2]−) with KC8 in toluene solution yields the complex [LtBuNi(toluene)], 1, where toluene is bound in a η2 mode via a C═C unit of the aromatic ring, as revealed by single-crystal X-ray crystallography and DFT calculations (B3LYP/6-31G*). Performing the same reaction in hexane as the solvent did not lead to a traceable product, so that the β-diketiminato ligand system was changed from LtBu to the less bulky LMe (LMe = [HC(CMeNC6H3(iPr)2)2]−). Reduction of [LMeNiBr]2 with KC8 in diethyl ether led to [LMeNi]2, 2, with intramolecular Ni−aryl interactions, while employment of [LMeNi(μ-Br)2Li(thf)2] as a precursor for a reaction with KC8 in OEt2 led to the complex [LMeNi(μ-Br)Li(thf)2]2, 3. Both complexes 2 and 3 could be fully characterized, also with the aid of XRD, and their reactivity with respect to H2 and N2 was examined. It turned out that they oxidatively add H2 to give the known compound [LMeNi(μ-H)]2, I, while the reaction with N2 provides the dinitrogen complex [(LMeNi)2(N2)], 4.

• Die Rolle von Radikalen bei metallvermittelten Oxygenierungen

  2003

  Angewandte Chemie · 80 Zitationen · DOI

  Abstract Metallvermittelte Oxofunktionalisierungen organischer Substrate sind von fundamentaler Bedeutung – in der Natur genauso wie in Hochschul‐ und Industrielaboratorien. Ungeachtet dessen sind die Mechanismen dieser Reaktionen rätselhaft geblieben, und nur wenige Prozesse werden im Detail verstanden. Dank intensiver Forschung konnte der Wissensstand in den letzten Jahren aber erheblich verbessert werden: So wurde gezeigt, dass viele Oxygenierungen über Radikalintermediate verlaufen – mitunter auch dann, wenn eine vergleichsweise hohe Selektivität Gegenteiliges vermuten lässt. Das zeigen Beispiele aus den unterschiedlichsten Bereichen: von molekularen Metalloxokomplexen, gasförmigen und matrixisolierten Spezies über das Reaktionsverhalten von Metalloenzymen bis hin zu Prozessen an Festkörperoberflächen. Der vorliegende Aufsatz beleuchtet die Vielfalt dieser Systeme und vermittelt einen Überblick über allgemein gültige Reaktionsmuster und Prinzipien sowie einige noch ungelöste Probleme.

• The Activation of Sulfur Hexafluoride at Highly Reduced Low‐Coordinate Nickel Dinitrogen Complexes

  2014

  Angewandte Chemie International Edition · 78 Zitationen · DOI

  The greenhouse gas sulfur hexafluoride is the common standard example in the literature of a very inert inorganic small molecule that is even stable against O2 in an electric discharge. However, a reduced β-diketiminate nickel species proved to be capable of converting SF6 into sulfide and fluoride compounds at ambient standard conditions. The fluoride product complex features an unprecedented [NiF](+) unit, where the Ni atom is only three-coordinate, while the sulfide product exhibits a rare almost linear [Ni(μ-S)Ni](2+) moiety. The reaction was monitored applying (1)H NMR, IR and EPR spectroscopic techniques resulting in the identification of an intermediate nickel complex that gave insight into the mechanism of the eight-electron reduction of SF6.

• Dinuclear Zinc Complexes Based on Parallel β-Diiminato Binding Sites:  Syntheses, Structures, and Properties as CO₂/Epoxide Copolymerization Catalysts

  2007

  Organometallics · 78 Zitationen · DOI

  With the background that β-diketiminato zinc complexes efficiently catalyze the CO2/epoxide copolymerization via a mechanism involving two catalyst molecules, a ligand system containing two parallel β-diiminato binding sites linked by a xanthene backbone ([RXanthdim]2- with residues R = 2,3-dimethylphenyl and 2,4-difluorophenyl at the iminato units, respectively) was investigated with respect to its zinc coordination chemistry. The corresponding diimines [RXanthdim]H2 were treated with diethylzinc to yield the complexes [Me2C6H3Xanthdim](ZnEt)2, 4, and [F2C6H3Xanthdim](ZnEt(thf))2, 5, respectively. In order to convert these compounds into polymerization catalysts, they were subsequently treated with SO2, which indeed resulted in the corresponding ethylsulfinates. Due to aggregation via intermolecular bridging of ethylsulfinate ligands, the product after the reaction of 5 represents an insoluble coordination polymer. Aggregation does take place also for the primary product obtained from the reaction of 4, as evidenced by the isolation of the tetramer [{[Me2C6H3Xanthdim]Zn2(μ-O2SEt)}μ-O2SEt]4, 6, and the precipitation of an insoluble solid on storing of such mixtures. 4, 5, and 6 display moderate activities as catalysts for the copolymerization of cyclohexene oxide and CO2. A bimodal molecular weight distribution points to two effective mechanisms, one of which probably involves two cooperating Zn centers as anticipated. Possible structural reasons for these catalytic results are discussed.

• OO Bond Activation in Heterobimetallic Peroxides: Synthesis of the Peroxide [LNi(μ,η²:η²‐O₂)K] and its Conversion into a Bis(μ‐Hydroxo) Nickel Zinc Complex

  2009

  Angewandte Chemie International Edition · 72 Zitationen · DOI

  O2 takes activation lessons: OO bond activation can be achieved depending on the nature of the heterometal M in [LNi(μ,η2:η2-O2)M] complexes. The reduction of the nickel(II) superoxide 1 with potassium affords the peroxide 2, which, upon replacement of the K+ ion in 2 by the non-redox-active L′Zn+ ion, leads to transient 3, which subsequently abstracts two solvent hydrogen atoms to give the heterobimetallic complex 4. L, L′=β-diketiminates. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

• N₂ Activation in Ni^I–NN–Ni^I Units: The Influence of Alkali Metal Cations and CO Reactivity

  2011

  Zeitschrift für anorganische und allgemeine Chemie · 66 Zitationen · DOI

  Abstract After single electron reduction of the dinitrogen complex [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( I ) with KC 8 , reaction of the resulting compound K[L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( II ) with sodium sand yields KNa[L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( 1 ), which contains two different alkali metal ions. Treatment of I with two equivalents of sodium sand leads to the symmetric complex Na 2 [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( 2 ). Complexes 1 and 2 were investigated by single crystal X‐ray diffraction analysis as well as by Raman spectroscopy, and the results were compared with the data of K 2 [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] ( III ), which contains two K + ions. Thus, it became obvious that the nature of the alkali metal ion M in compounds M 2 [L t Bu Ni(μ‐η 1 :η 1 ‐N 2 )NiL t Bu ] has hardly any influence on the degree of NN bond activation. Furthermore, it was shown that treatment of the dinickel(I) complex III with CO leads to the dinickel(0) compound K 2 [L t Bu Ni(CO)] 2 ( 4 ) and N 2 . Reaction of the unreduced dinickel(I) complex I with CO leads to a more simple replacement of the N 2 ligand and formation of [L t Bu Ni(CO)] ( 3 ).

• Shining light on integrity of a tetracobalt-polyoxometalate water oxidation catalyst by X-ray spectroscopy before and after catalysis

  2013

  Chemical Communications · 65 Zitationen · DOI

  Modification of the Co-oxo cores of cobalt-polyoxometalate water oxidation catalysts is detectable by X-ray absorption spectroscopy (XAS) as demonstrated by comparison of Na10[Co4(H2O)2(PW9O34)2] (1) and Na17[((Co(H2O))Co2PW9O34)2(PW6O26)] (2). XAS reveals the integrity of 1 uncompromised by oxidant-driven water oxidation, which proceeds without formation of catalytic cobalt oxide.

• Mono- and Dinuclear Oxovanadium(V)calixarene Complexes and Their Activity as Oxidation Catalysts

  2006

  Inorganic Chemistry · 65 Zitationen · DOI

  The background of the investigation is constituted by reactive moieties and intermediates playing relevant roles on the surfaces of vanadiumoxide-based catalysts during the oxygenation/dehydrogenation of organic substrates. With the aim of modeling such species, a series of mono- and dinuclear charged and uncharged vanadium oxo complexes containing p-tert-butylated calix[4]arene and calix[8]arene ligands (denoted H4B and H8B' ', respectively, in the protonated forms) has been synthesized and characterized: PPh4[O=VB] ((PPh41), O=VB(OAc) (2), PPh4[O2V2HB' '] (3), and [mu-O(O=V(OMe))2B(Me2)] (4), where superscripts OAc and Me2 indicate that one or two protons of H4B are substituted by these residues, respectively. These compounds were analyzed both in solution and by means of single-crystal X-ray crystallography; it turned out that the crystal structures are retained on dissolution (2 changed only from the paco to the cone structure). In the case of 4, it could be shown that the bulk product consists of a mixture of two isomers (4t and 4c) differing in the relative positions of the vanadium-bound methoxy groups. Subsequently, all compounds were tested as catalysts for the oxidation of alcohols with O2. It turned out that the two dinuclear complexes efficiently catalyze the oxidation of 1-phenyl-1-propargyl alcohol and fluorenol; in addition, they even show some activity with respect to the oxidation of dihydroanthracene. This may hint to a higher activity of dinuclear sites on the surfaces of heterogeneous catalysts as well.

• Cyanate Formation via Photolytic Splitting of Dinitrogen

  2021

  JACS Au · 63 Zitationen · DOI

  Light-driven N₂ cleavage into molecular nitrides is an attractive strategy for synthetic nitrogen fixation. However, suitable platforms are rare. Furthermore, the development of catalytic protocols via this elementary step suffers from poor understanding of N-N photosplitting within dinitrogen complexes, as well as of the thermochemical and kinetic framework for coupled follow-up chemistry. We here present a tungsten pincer platform, which undergoes fully reversible, thermal N₂ splitting and reverse nitride coupling, allowing for experimental derivation of thermodynamic and kinetic parameters of the N-N cleavage step. Selective N-N splitting was also obtained photolytically. DFT computations allocate the productive excitations within the {WNNW} core. Transient absorption spectroscopy shows ultrafast repopulation of the electronic ground state. Comparison with ground-state kinetics and resonance Raman data support a pathway for N-N photosplitting via a nonstatistically vibrationally excited ground state that benefits from vibronically coupled structural distortion of the core. Nitride carbonylation and release are demonstrated within a full synthetic cycle for trimethylsilylcyanate formation directly from N₂ and CO.

• Utilizing the Trispyrazolyl Borate Ligand for the Mimicking of O₂-Activating Mononuclear Nonheme Iron Enzymes

  2015

  Accounts of Chemical Research · 63 Zitationen · DOI

  Mononuclear, O2-activating nonheme iron enzymes are a fascinating class of metalloproteines, capable of realizing the most different reactions, ranging from C-H activation, via O atom transfer to C-C bond cleavage, in the course of O2 activation. They can lead us the way to achieve similar reactions with comparable efficiency and selectivity in chemical laboratories, which would be highly desirable aiming at accessing value-added products or to achieve degradation of unwanted compounds. Hence, these enyzmes motivate attempts to construct artificial low-molecular weight analogues, mimicking structural or functional characteristics. Such models can, for instance, provide insights about which of the features inherent to an active site are essential and guarantee the enzyme function, and from this kind of information the minimal requirements for a biomimetic or bioinspired complex that may be applied in catalysis can be derived. On the other hand, they can contribute to an understanding of the enzyme functioning. In order to create such replicates, it is important to faithfully mimic the surroundings of the iron centers in their active sites. Most of them feature two histidine residues and one carboxylate donor, while a few exhibit a deceptively simple (His)3Fe active site. For the simulation of these, the trispyrazolyl borate ligand (Tp) particularly offers itself, as the facial arrangement of three pyrazole donors is reminiscent of the three histidine-derived imidazole donors. The focus of this Account will be on bioinorganic/biomimetic research from our laboratory utilizing Tp ligands to develop molecular models for (i) two representatives of the (His)3Fe-enzyme family, namely, the cysteine dioxygenase (CDO) and acetyl acetone dioxygenase (Dke1), (ii) a related but less well-explored variant of the CDO-the 2-aminoethanethiol dioxygenase-as well as (iii) the 2-His-1-carboxylate representative 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO). The CDO catalyzes the dioxygenation of cysteine with O2 to give cysteine sulfinic acid, which could be mimicked at TpFe units in a realistic manner. Furthermore, the successful dioxygenation of 2-aminoethanethiol at the same complex metal fragments lends further support to the hypothesis that the active sites of CDO and the one of 2-aminoethanethiol dioxygenase, whose structure is unknown, are quite similar. Dke1 is capable of cleaving diketones and ketoesters to give the corresponding carboxylic acids and α-keto aldehydes, and Tp-based models have achieved comparable C-C bond cleavage reactions. The ACCO develops ethylene from ACC in the course of oxidation, and recently this has been achieved the first time for a TpFe model, too.

• Ein zweikerniger Nickel(I)‐Distickstoffkomplex und seine Reduktion in Einelektronenschritten

  2009

  Angewandte Chemie · 63 Zitationen · DOI

  Abstract Elektron für Elektron: β‐Diketiminatonickel(I)‐Komplexfragmente sind dazu in der Lage, Distickstoff durch Koordination zu aktivieren. Der entstehende Komplex kann in zwei Einelektronenschritten reduziert werden, wodurch die N‐N‐Bindung weiter aktiviert wird. Das Bild zeigt die Molekülstruktur des einfach reduzierten Komplexes mit μ‐η 1 :η 1 ‐gebundenem N 2 . magnified image

• Low‐Molecular‐Weight Analogues of the Soluble Methane Monooxygenase (sMMO): From the Structural Mimicking of Resting States and Intermediates to Functional Models

  2009

  Chemistry - A European Journal · 63 Zitationen · DOI

  The active centre of sMMO contains a diiron core ligated by histidine and glutamate residues, which is capable of catalysing a remarkable reaction: the oxidation of methane with O(2) yielding methanol. This review describes the results of efforts to prepare low-molecular-weight analogues of this active site directing towards 1) the assignment of the spectroscopic signatures identified for certain intermediates of the sMMO catalytic cycle to structural features and 2) the synthesis of molecular compounds that can mimic the reactivity. The historical development of the model chemistry, which is subdivided into structural and functional mimicking, is illustrated and achievements reached so far are highlighted.

• A low-coordinate nickel(ii) hydride complex and its reactivity

  2008

  Dalton Transactions · 61 Zitationen · DOI

  The preparation of a novel dinuclear nickel(ii) hydride complex and its reactivity that often leads to nickel(i) compounds is described.

• Hydride Binding to the Active Site of [FeFe]-Hydrogenase

  2014

  Inorganic Chemistry · 60 Zitationen · DOI

  [FeFe]-hydrogenase from green algae (HydA1) is the most efficient hydrogen (H2) producing enzyme in nature and of prime interest for (bio)technology. Its active site is a unique six-iron center (H-cluster) composed of a cubane cluster, [4Fe4S]H, cysteine-linked to a diiron unit, [2Fe]H, which carries unusual carbon monoxide (CO) and cyanide ligands and a bridging azadithiolate group. We have probed the molecular and electronic configurations of the H-cluster in functional oxidized, reduced, and super-reduced or CO-inhibited HydA1 protein, in particular searching for intermediates with iron-hydride bonds. Site-selective X-ray absorption and emission spectroscopy were used to distinguish between low- and high-spin iron sites in the two subcomplexes of the H-cluster. The experimental methods and spectral simulations were calibrated using synthetic model complexes with ligand variations and bound hydride species. Distinct X-ray spectroscopic signatures of electronic excitation or decay transitions in [4Fe4S]H and [2Fe]H were obtained, which were quantitatively reproduced by density functional theory calculations, thereby leading to specific H-cluster model structures. We show that iron-hydride bonds are absent in the reduced state, whereas only in the super-reduced state, ligand rotation facilitates hydride binding presumably to the Fe-Fe bridging position at [2Fe]H. These results are in agreement with a catalytic cycle involving three main intermediates and at least two protonation and electron transfer steps prior to the H2 formation chemistry in [FeFe]-hydrogenases.

• A Trispyrazolylborato Iron Cysteinato Complex as a Functional Model for the Cysteine Dioxygenase

  2012

  Angewandte Chemie International Edition · 59 Zitationen · DOI

  The natural paragon taken seriously: A trispyrazolylborato cysteinato iron complex not only excellently mimics the active site structure of cysteine dioxygenase (see picture: both structures superimposed): a dioxygenation of cysteinate occurs on treatment with O2, and hence, the system represents the hitherto most realistic model for cysteine dioxygenase. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

• Bundesanstalt für Materialforschung und -prüfung

  SFB 1109/1: Molekulare Einblicke in Metalloxid-Wasser-Systeme: Strukturelle Evolution, Grenzflächen und Auflösung

  other

• Charité – Universitätsmedizin Berlin

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  university

• Freie Universität Berlin

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  university

• Fritz-Haber-Institut der Max-Planck-Gesellschaft

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  other

• Helmholtz-Zentrum Berlin für Materialien und Energie

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  other

• Leibniz-Forschungsinstitut für Molekulare Pharmakologie

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  other

• Max-Planck-Institut für Kolloid- und Grenzflächenforschung

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  other

• Technische Universität Berlin

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  university

• Universität Potsdam

  EXC 314/1: Die Aufklärung des photo-induzierten Assemblierungsmechanismus, ausgehend von nativen und modifizierten Wasseroxidations-Katalysatoren des Photosystem II (AG Zouni) Biokatalytische Kopplung von Photosystem I mit FDH und CO-DH Superkomplexen

  university

Name

Prof. Dr. Christian Limberg

Titel

Prof. Dr.

Fakultät

Mathematisch-Naturwissenschaftliche Fakultät

Institut

Institut für Chemie

Arbeitsgruppe

Anorganische und Allgemeine Chemie I

Telefon

+49 30 2093-7382

HU-FIS-Profil

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26.4.2026, 01:08:36