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  • 1
    Online Resource
    Online Resource
    Organometallic Oxidation Catalysis (2007)
    Berlin [u.a.] : Springer
    Details
    UID:
    b3kat_BV036650740
    Format: 1 Online-Ressource
    Edition: Online-Ausgabe Springer ebook collection / Chemistry and Materials Science 2005-2008 Sonstige Standardnummer des Gesamttitels: 041171-1
    ISBN: 9783540372103
    Series Statement: Topics in Organometallic Chemistry 22
    Additional Edition: Reproduktion von Meyer, Franc, 1965- Organometallic Oxidation Catalysis 2007
    Additional Edition: Erscheint auch als Druckausgabe ISBN 978-3-540-37209-7
    Language: English
    Subjects: Chemistry/Pharmacy
    RVK:
    VE 7040
    RVK:
    VH 9700
    RVK:
    VK 5500
    Keywords: Oxidation ; Katalyse ; Metallorganische Verbindungen ; Aufsatzsammlung ; Aufsatzsammlung
    DOI: 10.1007/11603818
    URL: Volltext
    URL: Volltext  (lizenzpflichtig)
    URL: Inhaltstext
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    HWR Berlin
    UB Potsdam
    TH Brandenburg
    HTW Berlin
    TH Wildau
    BTU Cottbus
    BHT
  • 2
    Online Resource
    Online Resource
    Organometallic Oxidation Catalysis (2007)
    Berlin, Heidelberg :Springer Berlin Heidelberg,
    Details
    UID:
    almahu_9947364683102882
    Format: XI, 253 p. , online resource.
    ISBN: 9783540372103
    Series Statement: Topics in Organometallic Chemistry, 22
    Content: Eighty per cent of all compounds produced in the chemical and pharmaceutical industries require at least one essential catalytic step during their synthesis. At the same time the use of hydrocarbons as a feed-stock for commodity and fine chemicals typically requires an oxidation step, which is usually mediated by a transition metal compound. Consequently oxidation catalysis is a major research field in chemistry, both in academia and in industry. In many such processes, species with metal-carbon bonds are formed as key intermediates, and these processes represent the primary focus of this volume. An important aspect covered by some of the expert contributors is the use of organic ligands - and thus organometallic complex metal fragments - to achieve efficient oxidation catalysis. It has not been self-evident that organometallic complexes can survive the conditions necessary for polar oxygen-transfer reactions, but research over the last decade concerning oxo and peroxo complexes functionalized by organic ligands has clearly shown that relatively non-polar M-C bonds can be quite stable in the presence of oxidants and protic media, and that they may even be essential for the favourable activity and life-time of a catalyst. Also considered in this context is the oxidation chemistry of basic organometallic species in the gas phase, as this may reveal fundamental characteristics inherent to oxidation catalysts.
    Note: Intrinsic Mechanisms of Oxidation Reactions as Revealed by Gas-Phase Experiments -- Dioxygen Activation by Organometallics of Early Transition Metals -- Organorhenium and Organomolybdenum Oxides as Heterogenised Catalysts -- The SOHIO Process as an Inspiration for Molecular Organometallic Chemistry -- Catalysis and Organometallic Chemistry of Rhodium and Iridium in the Oxidation of Organic Substrates -- The Role of NHC Ligands in Oxidation Catalysis -- Palladium-Catalyzed Oxidation Reactions: Comparison of Benzoquinone and Molecular Oxygen as Stoichiometric Oxidants -- Homogeneous Copper-Catalyzed Oxidations.
    In: Springer eBooks
    Additional Edition: Printed edition: ISBN 9783540372097
    Language: English
    Subjects: Chemistry/Pharmacy
    RVK:
    VK 5500
    Keywords: Aufsatzsammlung
    DOI: 10.1007/11603818
    URL: http://dx.doi.org/10.1007/11603818
    URL: Volltext
    URL: Cover
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    Stabi Berlin
    HU Berlin
  • 3
    Online Resource
    Online Resource
    Organometallic oxidation catalysis / (2007)
    Berlin, Germany ; : Springer,
    Details
    UID:
    almafu_9958083812202883
    Format: 1 online resource (257 p.)
    Edition: 1st ed. 2007.
    ISBN: 1-280-74593-2 , 9786610745937 , 3-540-37210-5
    Series Statement: Topics in organometallic chemistry ; 22
    Content: Eighty per cent of all compounds produced in the chemical and pharmaceutical industries require at least one essential catalytic step during their synthesis. At the same time the use of hydrocarbons as a feed-stock for commodity and fine chemicals typically requires an oxidation step, which is usually mediated by a transition metal compound. Consequently oxidation catalysis is a major research field in chemistry, both in academia and in industry. In many such processes, species with metal-carbon bonds are formed as key intermediates, and these processes represent the primary focus of this volume. An important aspect covered by some of the expert contributors is the use of organic ligands - and thus organometallic complex metal fragments - to achieve efficient oxidation catalysis. It has not been self-evident that organometallic complexes can survive the conditions necessary for polar oxygen-transfer reactions, but research over the last decade concerning oxo and peroxo complexes functionalized by organic ligands has clearly shown that relatively non-polar M-C bonds can be quite stable in the presence of oxidants and protic media, and that they may even be essential for the favourable activity and life-time of a catalyst. Also considered in this context is the oxidation chemistry of basic organometallic species in the gas phase, as this may reveal fundamental characteristics inherent to oxidation catalysts.
    Note: Description based upon print version of record. , Intrinsic Mechanisms of Oxidation Reactions as Revealed by Gas-Phase Experiments -- Dioxygen Activation by Organometallics of Early Transition Metals -- Organorhenium and Organomolybdenum Oxides as Heterogenised Catalysts -- The SOHIO Process as an Inspiration for Molecular Organometallic Chemistry -- Catalysis and Organometallic Chemistry of Rhodium and Iridium in the Oxidation of Organic Substrates -- The Role of NHC Ligands in Oxidation Catalysis -- Palladium-Catalyzed Oxidation Reactions: Comparison of Benzoquinone and Molecular Oxygen as Stoichiometric Oxidants -- Homogeneous Copper-Catalyzed Oxidations. , English
    Additional Edition: ISBN 3-642-07206-2
    Additional Edition: ISBN 3-540-37209-1
    Language: English
    DOI: 10.1007/11603818
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    FU Berlin
    Charité
  • 4
    Online Resource
    Online Resource
    Spectroscopic Properties of a Biologically Relevant [Fe2(μ‐O)2] Diamond Core Motif with a Short Iron‐Iron Distance (2023)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_27843
    Format: 1 Online-Ressource (6 Seiten)
    Content: Diiron cofactors in enzymes perform diverse challenging transformations. The structures of high valent intermediates (Q in methane monooxygenase and X in ribonucleotide reductase) are debated since Fe−Fe distances of 2.5–3.4 Å were attributed to “open” or “closed” cores with bridging or terminal oxido groups. We report the crystallographic and spectroscopic characterization of a FeIII2(μ-O)2 complex (2) with tetrahedral (4C) centres and short Fe−Fe distance (2.52 Å), persisting in organic solutions. 2 shows a large Fe K-pre-edge intensity, which is caused by the pronounced asymmetry at the TD FeIII centres due to the short Fe−μ−O bonds. A ≈2.5 Å Fe−Fe distance is unlikely for six-coordinate sites in Q or X, but for a Fe2(μ-O)2 core containing four-coordinate (or by possible extension five-coordinate) iron centres there may be enough flexibility to accommodate a particularly short Fe−Fe separation with intense pre-edge transition. This finding may broaden the scope of models considered for the structure of high-valent diiron intermediates formed upon O2 activation in biology.
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 62,10
    Language: English
    DOI: 10.18452/27183
    DOI: 10.1002/anie.202209437
    URN: urn:nbn:de:kobv:11-110-18452/27843-4
    URL: Volltext  (kostenfrei)
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    HU Berlin
  • 5
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    Online Resource
    Spektroskopische Eigenschaften eines biologisch‐relevanten [Fe2(μ‐O)2] Diamond‐Core‐Motivs mit einem kurzen Eisen‐Eisen‐Abstand (2023)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_27842
    Format: 1 Online-Ressource (7 Seiten)
    Content: Dieisen-Kofaktoren in Enzymen vollziehen diverse anspruchsvolle Transformationen. Die Strukturen hoch-valenter Intermediate (Q in der löslichen Methanmonooxygenase und X in der Ribonukleotidreduktase) sind Gegenstand aktueller Diskussionen, seit Fe-Fe-Abstände von 2.1–3.4 Å eine Zuordnung zu geöffneten und geschlossen Kernen mit verbrückenden oder terminalen Oxido-Gruppen in den aktiven Zentren ermöglichen. In dieser Studie berichten wir die kristallografische und spektroskopische Charakterisierung eines FeIII2(μ-O)2-Komplexes (2) mit tetraedrischen (4C) Zentren sowie einem geringen Fe-Fe-Abstand (2.52 Å), der in Lösungsmitteln beständig ist. 2 zeigt eine große Fe-K-Vorkanten-Intensität. Diese resultiert aus der starken Asymmetrie an den TD-FeIII-Zentren bedingt durch die kurzen Fe-μ-O-Bindungen. Während ein Fe-Fe-Abstand von ≈2.5 Å für sechsfach-koordinierte Zentren in Q und X unwahrscheinlich ist, könnte ein Fe2(μ-O)2-Kern mit vierfacher (oder möglicherweise auch fünffacher) Koordination flexibel genug sein, um eine kurze Fe-Fe-Separierung mit großer Vorkanten-Intensität zu ermöglichen. Diese Erkenntnis kann dazu beitragen, dass weitere Modelle für die Strukturen der hoch-valenten Dieisen-Intermediate, die sich im Zuge der biologischen O2-Aktivierung bilden, in Betracht gezogen werden.
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 135,10
    Language: German
    DOI: 10.18452/27182
    DOI: 10.1002/ange.202209437
    URN: urn:nbn:de:kobv:11-110-18452/27842-8
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    HU Berlin
  • 6
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    Online Resource
    Two Allogons of an O2-activating Bis(disiloxido)ferrate(II) Accessible Selectively just by Variation of the Crystallization Temperature (2023)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_29010
    Format: 1 Online-Ressource (6 Seiten)
    Content: Deprotonation of O(iPr2SiOH)2 (iPrLH2) with LiOtBu followed by reaction with FeCl2 in THF led to the complex [iPrL2Fe][Li(THF)2]2, 2, which represents a structural and spectroscopic model of the α‐Fe sites of Fe/ZSM‐5. Reaction with O2 in THF solution proceeds rather fast and is complete within 200 ms; an intermediate O2 adduct could not be identified by stopped‐flow methods. Cooling blue solutions of 2 to −80 °C led to the growth of blue crystals of 2⋅THF, the analysis of which by XRD revealed a FeO4 core that is somewhat distorted from planarity towards a tetrahedral structure. By contrast, cooling such solutions to −30 °C led to pink crystals of an allogon featuring a perfectly square planar FeO4 entity. Hence, 2 represents a unique case where two different structural isomers (allogons) can be crystallized from the same solvent selectively, controlled by the temperature. DFT calculations were performed to understand this finding.
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 30,12
    Language: English
    DOI: 10.18452/28363
    DOI: 10.1002/chem.202303614
    URN: urn:nbn:de:kobv:11-110-18452/29010-9
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    HU Berlin
  • 7
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    Online Resource
    NMR spectroscopic investigations on the successive implementation of nickel and zinc ions to a NacNac-dibenzofuran-Br ligand precursor (2023)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_28974
    Format: 1 Online-Ressource (6 Seiten)
    Content: The ligand precursor HNacNac-dibenzofuran-Br, LH, was synthesized by the condensation of 6-bromo-4-dibenzofuranamine and 4-(N-(mesityl)amino)pent-3-en-2-one with the aim of preparing heterodinuclear nickel/zinc complexes in two successive steps. Reacting LH with Zn(HMDS)2, Zn(C6F5)2 and Zn(C2H5)2 led to the respective X-Zn-NacNac-dibenzofuran-Br complexes (X=HMDS (2), C6F5 (3), Et (4)). However, in case of 2 and 3 the subsequent treatment with Ni(COD)2/TMEDA did not lead to any conversion, probably as the steric bulk imposed by the NacNac-Zn-X entities was too high. 4 did react with Ni(COD)2/TMEDA, likely in the envisaged manner, but apparently the targeted product complex Et-Zn-NacNac-dibenzofuran-Ni(TMEDA)Br, once formed, immediately reacts further via a Negishi coupling reaction, so that Br-Zn-NacNac-dibenzofuran-Et (5) is formed. The reaction of 4 with triethylammonium bromide led to the formation of the Br-Zn-NacNac-dibenzofuran-Br (6) complex that could be reacted with Ni(COD)2/TMEDA successfully. All attempts to purify the product led to Zn(NacNac-dibenzofuran-Ni(TMEDA)Br)2, which is insoluble in THF and thus drives a dismutation reaction.
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 649,23
    Language: English
    DOI: 10.18452/28323
    DOI: 10.1002/zaac.202300178
    URN: urn:nbn:de:kobv:11-110-18452/28974-3
    URL: Volltext  (kostenfrei)
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    HU Berlin
  • 8
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    Online Resource
    Unravelling the Role of the Pentafluoroorthotellurate Group as a Ligand in Nickel Chemistry (2022)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_26466
    Format: 1 Online-Ressource (8 Seiten)
    Content: The pentafluoroorthotellurate group (teflate, OTeF5) is able to form species, for which only the fluoride analogues are known. Despite nickel fluorides being widely investigated, nickel teflates have remained elusive for decades. By reaction of [NiCl4]2− and neat ClOTeF5, we have synthesized the homoleptic [Ni(OTeF5)4]2− anion, which presents a distorted tetrahedral structure, unlike the polymeric [NiF4]2−. This high‐spin complex has allowed the study of the electronic properties of the teflate group, which can be classified as a weak/medium‐field ligand, and therefore behaves as the fluoride analogue also in ligand‐field terms. The teflate ligands in [NEt4]2[Ni(OTeF5)4] are easily substituted, as shown by the formation of [Ni(NCMe)6][OTeF5]2 by dissolving it in acetonitrile. Nevertheless, careful reactions with other conventional ligands have enabled the crystallization of nickel teflate complexes with different coordination geometries, i.e. [NEt4]2[trans‐Ni(OEt2)2(OTeF5)4] or [NEt4][Ni(bpyMe2)(OTeF5)3].
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 28,63
    Language: English
    DOI: 10.18452/25793
    DOI: 10.1002/chem.202202016
    URN: urn:nbn:de:kobv:11-110-18452/26466-5
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    HU Berlin
  • 9
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    Online Resource
    Stabilizing Monoatomic Two-Coordinate Bismuth(I) and Bismuth(II) Using a Redox Noninnocent Bis(germylene) Ligand (2024)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_29326
    Format: 1 Online-Ressource (12 Seiten)
    ISSN: 0002-7863 , 0002-7863
    Content: The formation of isolable monatomic BiI complexes and BiII radical species is challenging due to the pronounced reducing nature of metallic bismuth. Here, we report a convenient strategy to tame BiI and BiII atoms by taking advantage of the redox noninnocent character of a new chelating bis(germylene) ligand. The remarkably stable novel BiI cation complex 4, supported by the new bis(iminophosphonamido-germylene)xanthene ligand [(P)GeII(Xant)GeII(P)] 1, [(P)GeII(Xant)GeII(P) = Ph2P(NtBu)2GeII(Xant)GeII(NtBu)2PPh2, Xant = 9,9-dimethyl-xanthene-4,5-diyl], was synthesized by a two-electron reduction of the cationic BiIIII2 precursor complex 3 with cobaltocene (Cp2Co) in a molar ratio of 1:2. Notably, owing to the redox noninnocent character of the germylene moieties, the positive charge of BiI cation 4 migrates to one of the Ge atoms in the bis(germylene) ligand, giving rise to a germylium(germylene) BiI complex as suggested by DFT calculations and X-ray photoelectron spectroscopy (XPS). Likewise, migration of the positive charge of the BiIIII2 cation of 3 results in a bis(germylium)BiIIII2 complex. The delocalization of the positive charge in the ligand engenders a much higher stability of the BiI cation 4 in comparison to an isoelectronic two-coordinate Pb0 analogue (plumbylone; decomposition below −30 °C). Interestingly, 4[BArF] undergoes a reversible single-electron transfer (SET) reaction (oxidation) to afford the isolable BiII radical complex 5 in 5[BArF]2. According to electron paramagnetic resonance (EPR) spectroscopy, the unpaired electron predominantly resides at the BiII atom. Extending the redox reactivity of 4[OTf] employing AgOTf and MeOTf affords BiIII(OTf)2 complex 7 and BiIIIMe complex 8, respectively, demonstrating the high nucleophilic character of BiI cation 4.
    Content: Peer Reviewed
    In: Washington, DC : American Chemical Society, 146,9, Seiten 6025-6036, 0002-7863
    Language: English
    DOI: 10.18452/28737
    DOI: 10.1021/jacs.3c13016
    URN: urn:nbn:de:kobv:11-110-18452/29326-8
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  • 10
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    Online Resource
    Questing for homoleptic mononuclear manganese complexes with monodentate O-donor ligands (2024)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_29334
    ISSN: 2041-6520 , 2041-6520
    Content: Compounds containing Mn–O bonds are of utmost importance in biological systems and catalytic processes. Nevertheless, mononuclear manganese complexes containing all O-donor ligands are still rare. Taking advantage of the low tendency of the pentafluoroorthotellurate ligand (teflate, OTeF5) to bridge metal centers, we have synthesized two homoleptic manganese complexes with monomeric structures and an all O-donor coordination sphere. The tetrahedrally distorted MnII anion, [Mn(OTeF5)4]2−, can be described as a high spin d5 complex (S = 5/2), as found experimentally (magnetic susceptibility measurements and EPR spectroscopy) and using theoretical calculations (DFT and CASSCF/NEVPT2). The high spin d4 electronic configuration (S = 2) of the MnIII anion, [Mn(OTeF5)5]2−, was also determined experimentally and theoretically, and a square pyramidal geometry was found to be the most stable one for this complex. Finally, the bonding situation in both complexes was investigated by means of the Interacting Quantum Atoms (IQA) methodology and compared to that of hypothetical mononuclear fluoromanganates. Within each pair of [MnXn]2− (n = 4, 5) species (X = OTeF5, F), the Mn–X interaction is found to be comparable, therefore proving that the similar electronic properties of the teflate and the fluoride are also responsible for the stabilization of these unique species.
    Content: Peer Reviewed
    In: Cambridge : RSC Publishing, 15,15, Seiten 5564-5572, 2041-6520
    Language: English
    DOI: 10.18452/28748
    DOI: 10.1039/d4sc00543k
    URN: urn:nbn:de:kobv:11-110-18452/29334-2
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    HU Berlin
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