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Subject: search.filters.subject.540Start date: 2020Institute: search.filters.UBSInstitut.Institut für Anorganische ChemieAuthor: search.filters.author.Blickle, Svenja

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    Campherchinoniminliganden und ihr Elektronentransferverhalten unter Metallkoordination an Rhenium und Mangan
    (2021) Blickle, Svenja; Kaim, Wolfgang (Prof. Dr. phil. nat.)
    Die vorliegende Arbeit beschäftigt sich mit der Synthese und dem Koordinations- und Elektronentransferverhalten von neuen redoxaktiven Campherchinoniminliganden und deren Komplexe mit dem Metallkomplexfragment M(CO)3Cl mit M = Re, Mn. Der Fokus liegt dabei auf der Untersuchung der redoxchemischen Eigenschaften von dinuklearen Komplexen, bei welchen die Metalle über einen Bischelatliganden verbrückt sind. So konnten Einblicke in die elektronische Struktur der Verbindungen in neutraler, radikalanionischer und dianionischer Form gewonnen werden. Zur Charakterisierung dieser neuen Verbindungen kommen zum Einsatz: CHN-Elementaranalyse, Massenspektrometrie, Kristallstrukturanalyse, Cyclovoltammetrie, 1H-NMR-, IR-, UV/Vis/NIR- und EPR-Spektroskopie und Spektroelektrochemie. Die experimentellen Ergebnisse werden mit Hilfe von quantenchemischen Methoden (DFT) unterstützt. So konnte für diese Art von Verbindungen eine neue Art von gemischtvalenten Metallkomplexen etabliert werden: Die Reduktionen finden ligandenzentriert statt und die Ladungsverteilung der radikalanionischen Spezies konnte als asymmetrisch lokalisiert nachgewiesen werden. Somit handelt es sich bei den hier vorgestellten zweikernigen einfach reduzierten Komplexen um organisch-gemischtvalente Verbindungen unter homovalenter Metallkoordination.
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    The indigo isomer epindolidione as a redox‐active bridging ligand for diruthenium complexes
    (2021) Kumari, Maya; Bera, Sudip Kumar; Blickle, Svenja; Kaim, Wolfgang; Lahiri, Goutam Kumar
    Epindolidione (H2L), a heteroatom‐modified analogue of tetracene and a structural isomer of indigo, forms dinuclear complexes with [RuX2]2+, X=bpy (2,2′‐bipyridine, [1]2+) or pap (2‐phenylazopyridine, [2]2+), in its doubly deprotonated bridging form μ‐L2-. The dications in compounds meso‐[1](ClO4)2 and meso‐[2](ClO4)2, [X2Ru(μ‐L)RuX2](ClO4)2, contain five‐membered chelate rings N‐C-C‐O‐RuII with π bridged metals at an intramolecular distance of 7.19 Å. Stepwise reversible oxidation and reduction is mainly ligand centered (oxidation: L2-; reduction: X), as deduced from EPR of one‐electron oxidized and reduced intermediates and from UV/Vis/NIR spectroelectrochemistry, supported by TD‐DFT calculation results. The results for [1](ClO4)2 and [2](ClO4)2 are qualitatively similar to the ones observed with the deprotonated indigo‐bridged isomers with their six‐membered chelate ring structures, confirming the suitability of both π systems for molecular electronics applications, low‐energy absorptions, and multiple electron transfers.
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    Structural and oxidation state alternatives in platinum and palladium complexes of a redox‐active amidinato ligand
    (2021) Ehret, Fabian; Filippou, Vasileios; Blickle, Svenja; Bubrin, Martina; Záliš, Stanislav; Kaim, Wolfgang
    Reaction of [Pt(DMSO)2Cl2] or [Pd(MeCN)2Cl2] with the electron‐rich LH=N,N’‐bis(4‐dimethylaminophenyl)ethanimidamide yielded mononuclear [PtL2] (1) but dinuclear [Pd2L4] (2), a paddle‐wheel complex. The neutral compounds were characterized through experiments (crystal structures, electrochemistry, UV‐vis‐NIR spectroscopy, magnetic resonance) and TD‐DFT calculations as metal(II) species with noninnocent ligands L-. The reversibly accessible cations [PtL2]+ and [Pd2L4]+ were also studied, the latter as [Pd2L4][B{3,5‐(CF3)2C6H3}4] single crystals. Experimental and computational investigations were directed at the elucidation of the electronic structures, establishing the correct oxidation states within the alternatives [PtII(L-)2] or [Pt.(L )2], [PtII(L0.5-)2]+ or [PtIII(L-)2]+, [(PdII)2(μ‐L−)4] or [(Pd1.5)2(μ‐L0.75-)4], and [(Pd2.5)2(μ‐L-)4]+ or [(PdII)2(μ‐L0.75-)4]+. In each case, the first alternative was shown to be most appropriate. Remarkable results include the preference of platinum for mononuclear planar [PtL2] with an N‐Pt‐N bite angle of 62.8(2)° in contrast to [Pd2L4], and the dimetal (Pd24+→Pd25+) instead of ligand (L-→L ) oxidation of the dinuclear palladium compound.
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    Intramolecular charge transfer in ruthenium complexes [Ru(acac)2(ciq)] with ambidentate camphoriminoquinone (ciq) ligands
    (2021) Filippou, Vasileios; Blickle, Svenja; Bubrin, Martina; Kaim, Wolfgang
    Reaction of [Ru(acac)2(MeCN)2], acac−=acetylacetonate, with N‐phenylcamphoriminoquinone (pciq) or the new N‐(2‐thiomethylphenyl)‐camphoriminoquinone (tciq) produces complexes [Ru(acac)2(pciq)] and [Ru(acac)2(tciq)] with N,O or N,S coordination and E or Z configuration at the C=N bond, respectively. Oxidation state assignments in comparison with classical iminoquinone ligands are based on structural data in connection with DFT calculations. Reversible oxidation yields complex ions [RuIII(acac)2(pciq)]+ and [RuIII(acac)2(tciq)]+ as characterized by EPR, IR and UV‐vis‐NIR spectroelectrochemistry.