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End date: 2019 × Start date: 2010 × DDC: 540 × Subject: cobalt ×

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Now showing 1 - 6 of 6
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    Cobalt-Catalyzed Aqueous Dehydrogenation of Formic Acid
    (Weinheim : Wiley-VCH, 2019) Zhou, Wei; Wei, Zhihong; Spannenberg, Anke; Jiao, Haijun; Junge, Kathrin; Junge, Henrik; Beller, Matthias
    Among the known liquid organic hydrogen carriers, formic acid attracts increasing interest in the context of safe and reversible storage of hydrogen. Here, the first molecularly defined cobalt pincer complex is disclosed for the dehydrogenation of formic acid in aqueous medium under mild conditions. Crucial for catalytic activity is the use of the specific complex 3. Compared to related ruthenium and manganese complexes 7 and 8, this optimal cobalt complex showed improved performance. DFT computations support an innocent non-classical bifunctional outer-sphere mechanism on the triplet state potential energy surface. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    Nickel cobalt oxide hollow nanosponges as advanced electrocatalysts for the oxygen evolution reaction
    (Cambridge : Soc., 2015) Zhu, Chengzhou; Wen, Dan; Leubner, Susanne; Oschatz, Martin; Liu, Wei; Holzschuh, Matthias; Simon, Frank; Kaskel, Stefan; Eychmüller, Alexander
    A class of novel nickel cobalt oxide hollow nanosponges were synthesized through a sodium borohydride reduction strategy. Due to their porous and hollow nanostructures, and synergetic effects between their components, the optimized nickel cobalt oxide nanosponges exhibited excellent catalytic activity towards oxygen evolution reaction.
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    3,3′-Dimethyl-1,1′-methyl­enediimidazolium tetra­bromido­cobaltate(II)
    (Chester : IUCr, 2018) Peppel, Tim; Spannenberg, Anke
    The title compound, (C9H14N4)[CoBr4], was obtained as single crystals directly in very low yield as a side product in the reaction of 1,1′-bis­(1-methyl­imidazolium)acetate bromide and CoBr2. The title compound consists of an imidazolium-based dication and a tetra­bromido­cobaltate(II) complex anion, which are connected via C—H...Br inter­actions in the crystal. The dihedral angle between the imidazolium rings in the cation is 72.89 (16)°. The CoII ion in the anion is coordinated tetra­hedrally by four bromide ligands [Co—Br = 2.4025 (5)–2.4091 (5) Å and Br—Co—Br = 106.224 (17)–113.893 (17)°]. The compound exhibits a high melting point (>300°C) and is a light-blue solid under ambient conditions.
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    Crystal structure of tricarbonyl(N-diphenylphosphanyl-N,N'-diisopropyl-P-phenylphosphonous diamide-κ2 P,P')cobalt(I) tetracarbonylcobaltate(-I) toluene 0.25-solvate
    (Chester : International Union of Crystallography, 2014) Dura, L.; Spannenberg, A.; Beweries, T.
    The asymmetric unit of the title compound, [Co(C24H30N2P2)(CO)3][Co(CO)4]·0.25C7H8, consists of two crystallographically independent cations with similar conformations, two anions, and one-half of a toluene molecule disordered about an inversion centre. In the cations, a Co/P/N/P four-membered slightly bent metallacycle is the key structural element. The pendant NH group is not coordinated to the CoI atom, which displays a distorted trigonal-bipyramidal coordination geometry. Weak interionic hydrogen bonds are observed between the NH groups and a carbonyl group of the tetrahedral [Co(CO)4]- anions.
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    Conductive Self-Assembled Monolayers of Paramagnetic {CoIICo4III} and {Co4IICo2III} Coordination Clusters on Gold Surfaces
    (Lausanne : Frontiers Media, 2019) Schmitz, Sebastian; Qiu, Xinkai; Glöß, Maria; van Leusen, Jan; Izarova, Natalya V.; Nadeem, Muhammad Arif; Griebel, Jan; Chiechi, Ryan C.; Kögerler, Paul; Monakhov, Kirill Yu.
    Two polynuclear cobalt(II,III) complexes, [Co5(N3)4(N-n-bda)4(bza·SMe)2] (1) and [Co6(N3)4(N-n-bda)2(bza·SMe)5(MeOH)4]Cl (2), where Hbza·SMe = 4-(methylthio)benzoic acid and N-n-H2bda = N-n-butyldiethanolamine, were synthesized and fully characterized by various techniques. Compound 1 exhibits an unusual, approximately C2-symmetric {CoII Co4II } core of two isosceles Co3 triangles with perpendicularly oriented planes, sharing a central, high-spin CoII ion residing in a distorted tetrahedral coordination environment. This central CoII ion is connected to four outer, octahedrally coordinated low-spin CoIII ions via oxo bridges. Compound 2 comprises a semi-circular {Co4IICo2III } motif of four non-interacting high-spin CoII and two low-spin CoIII centers in octahedral coordination environments. Self-assembled monolayers (SAMs) of 1 and 2 were physisorbed on template-stripped gold surfaces contacted by an eutectic gallium-indium (EGaIn) tip. The acquired current density-voltage (I-V) data revealed that the cobalt-based SAMs are more electrically robust than those of the previously reported dinuclear {CuIILnIII} complexes with Ln = Gd, Tb, Dy, or Y (Schmitz et al., 2018a). In addition, between 170 and 220°C, the neutral, mixed-valence compound 1 undergoes a redox modification, yielding a {Co5}-based coordination cluster (1-A) with five non-interacting, high-spin octahedral CoII centers as indicated by SQUID magnetometry analysis in combination with X-ray photoelectron spectroscopy and infrared spectroscopy. Solvothermal treatment of 1 results in a high-nuclearity coordination cluster, [Co10(N3)2(N-n-bda)6(bza·SMe)6] (3), containing 10 virtually non-interacting high-spin CoII centers. © Copyright © 2019 Schmitz, Qiu, Glöß, van Leusen, Izarova, Nadeem, Griebel, Chiechi, Kögerler and Monakhov.
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    Effizienzsteigerung der Meeresforschungstechnik (VEM), Teilprojekt 4: Katalysatoren für Unterwasseranwendungen : Schlussbericht ; Laufzeit: 01.03.2008 - 28.02.2011
    (Hannover : Technische Informationsbibliothek (TIB), 2011) Surkus, Annette-Enrica; Junge, Henrik
    [no abstract available]