Browsing by Author "Rudel, Stefan S."

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    A 1D Coordination Polymer of UF5 with HCN as a Ligand
    (2017-01-05) Scheibe, Benjamin; Rudel, Stefan S.; Buchner, Magnus R.; Karttunen, Antti J.; Kraus, Florian; University of Marburg; Department of Chemistry; Department of Chemistry and Materials Science
    β-Uranium(V) fluoride was reacted with liquid anhydrous hydrogen cyanide to obtain a 1D coordination polymer with the composition (Formula presented.) [UF5(HCN)2], (Formula presented.) [UF4/1F2/2- (HCN)2/1], revealed by single-crystal X-ray structure determination. The reaction system was furthermore studied by means of vibrational and NMR spectroscopy, as well as by quantum chemical calculations. The compound presents the first described polymeric HCN Lewis adduct and the first HCN adduct of a uranium fluoride.
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    Complexes featuring a linear [N≡U≡N] core isoelectronic to the uranyl cation
    (Nature Publishing Group, 2020-10-01) Rudel, Stefan S.; Deubner, H. Lars; Müller, Matthias; Karttunen, Antti J.; Kraus, Florian; Department of Chemistry and Materials Science; Inorganic Materials Modelling; University of Marburg
    The aqueous chemistry of uranium is dominated by the linear uranyl cation [UO2]2+, yet the isoelectronic nitrogen-based analogue of this ubiquitous cation, molecular [UN2], has so far only been observed in an argon matrix. Here, we present three different complexes of [UN2] obtained by the reaction of the uranium pentahalides UCl5 or UBr5 with anhydrous liquid ammonia. The [UN2] moieties are linear, with the U atoms coordinated by five additional ligands (ammonia, chloride or bromide), resulting in a pentagonal bipyramidal coordination sphere that is also commonly adopted by the uranyl cation [UO2(L)5]2+ (L, ligand). In all three cases, the nitrido ligands are further coordinated through their lone pairs by the Lewis-acidic ligands [U(NH3)8]4+ to form almost linear, trinuclear complex cations. Those were characterized by single-crystal X-ray diffraction, Raman and infrared spectroscopy, 14N/15N isotope studies and quantum chemical calculations, which support the presence of two U≡N triple bonds within the [UN2] moieties. [Figure not available: see fulltext.]
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    NOUF6 Revisited
    (2016-07-14) Scheibe, Benjamin; Lippert, Sina; Rudel, Stefan S.; Buchner, Magnus R.; Burghaus, Olaf; Pietzonka, Clemens; Koch, Martin; Karttunen, Antti J.; Kraus, Florian; University of Marburg; Department of Chemistry
    We have synthesized NOUF6 by direct reaction of NO with UF6 in anhydrous HF (aHF). Based on the unit cell volume and powder diffraction data, the compound was previously reported to be isotypic to O2PtF6, however, detailed structural data, such as the atom positions and all information that can be derived from those, were unavailable. We have therefore investigated the compound by using single-crystal and powder X-ray diffraction, IR, Raman, NMR, EPR, and photoluminescence spectroscopy, magnetic measurements, as well as chemical analysis, density determination, and quantum chemical calculations.
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    Rb2[U(NH2)6], a Rubidium Hexaamidouranate(IV) obtained from the Reaction of UI3 with RbNH2 in Anhydrous Ammonia
    (WILEY-V C H VERLAG GMBH, 2020-07-31) Rudel, Stefan S.; Karttunen, Antti J.; Kraus, Florian; Department of Chemistry and Materials Science; Inorganic Materials Modelling; University of Marburg
    The pyrophoric compound Rb2[U(NH2)6] was obtained as a grey to black powder from the reaction of more than three equivalents of RbNH2 with UI3 in anhydrous liquid ammonia. During the process, UIII is oxidized to UIV and ammonia is reduced under evolution of H2. Rb2[U(NH2)6] crystallizes in the cubic crystal system, space group Fm3m, with the lattice parameter a = 9.7870(12) Å, V = 937.4(2) Å3, Z = 4 at T = 293 K. It is isotypic to K2PtCl6. The compound contains the unprecedented hexaamidouranate(IV) anion [U(NH2)6]2–.
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    Reactions in Anhydrous Liquid Ammonia : Syntheses and Crystal Structures of [M(NH3)8]I2 (M = Eu, Yb) with Bicapped Trigonal-Prismatic Octaammine Lanthanoid(II) Cations
    (WILEY-V C H VERLAG GMBH, 2020-08-31) Rudel, Stefan S.; Graubner, Tim; Karttunen, Antti J.; Kraus, Florian; University of Marburg; Department of Chemistry and Materials Science
    The compounds [M(NH3)8]I2 (M = Eu, Yb) were obtained from reactions in anhydrous liquid ammonia solutions as side products. They were characterized by single-crystal X-ray diffraction and found to be isotypic to the compounds [Ca(NH3)8]X2 (X = Cl, Br, I). The coordination sphere of the lanthanoid(II) cations is not square-antiprismatic but much better described as bicapped trigonal-prismatic. In contrast, quantum-chemical gas-phase calculations show the square-antiprismatic coordination polyhedron (point group S8) to be energetically favored over the bicapped trigonal prism and the latter is not even a true local minimum. Obviously, hydrogen bonding and eventually other weak interactions have an impact on the observed bicapped trigonal-prismatic coordination sphere of the [M(NH3)8]2+ cations in the solid state.
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    Reactions of [SiF4(NH3)2] with Fluorides AF (A = Li-Cs, Tl, NH4) in Liquid NH3: A [NH4(NH3)2]+ Cation and a Thallophilic Interaction in [Tl2(NH3)6]2+
    (AMERICAN CHEMICAL SOCIETY, 2021-10-04) Rudel, Stefan S.; Graubner, Tim; Karttunen, Antti J.; Dehnen, Stefanie; Kraus, Florian; University of Marburg; Department of Chemistry and Materials Science
    We investigated whether [SiF4(NH3)2] can act as a fluoride-ion acceptor in its reactions with the fluorides AF (A = Li-Cs, Tl, NH4) in anhydrous liquid ammonia (NH3). While LiF and NaF did not react, we obtained the compounds K[SiF5(NH3)], Rb[SiF5(NH3)], and Cs[SiF5(NH3)], as well as [NH4(NH3)2]2[SiF6] and [Tl2(NH3)6][SiF6]·2NH3, from the other starting materials and characterized them by either single-crystal or powder X-ray diffraction. The compound [NH4(NH3)2]2[SiF6] contains the very rarely observed hydrogen-bonded, C2v-symmetric diammine ammonium cation [NH4(NH3)2]+, and the compound [Tl2(NH3)6][SiF6]·2NH3 is an example for an uncommon Tl(I)-Tl(I) interaction. This "thallophilic" interaction was investigated with quantum-chemical methods.
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    Uranium Cyanides from Reactions in Liquid Ammonia Solution
    (Wiley-VCH Verlag, 2024-06-03) Graubner, Tim; Rudel, Stefan S.; Ivlev, Sergei I.; Karttunen, Antti J.; Kraus, Florian; Department of Chemistry and Materials Science; Inorganic Materials Modelling; University of Marburg
    Reactions of uranium tri- and tetrahalides, UBr3, UI3, UCl4, and UI4, with different cyanides MCN (M=K, Ag) in liquid anhydrous ammonia led to three novel uranium(IV) cyanide compounds. The reaction of UCl4 in the presence of KCN resulted in the compound [U(CN)(NH3)8]Cl3 ⋅ 3NH3, while UBr3 and UI3 were oxidized in the presence of AgCN to form the compounds (Formula presented.) (μ-CN){(H3N)5U(μ-NH2)3U(NH3)5}]Br4 ⋅ 2NH3, and (Formula presented.) (μ-CN){(H3N)5U(μ-NH2)3U(NH3)5}]I4 ⋅ 2NH3. The reaction of UI4 with KCN in aNH3 also yielded the compound (Formula presented.) (μ-CN){(H3N)5U(μ-NH2)3U(NH3)5}]I4 ⋅ 2NH3. The compounds (Formula presented.) (μ-CN){(H3N)5U(μ-NH2)3U(NH3)5}]X4 ⋅ 2NH3 (X=Br, I) crystallize in different space groups, Pmn21 (no. 31) and Imm2 (no. 44), respectively. In both cases, the (Formula presented.) (μ-CN){(H3N)5U(μ-NH2)3U(NH3)5}]4+ cation forms infinite strands. We conducted quantum-chemical calculations and Intrinsic Bond Orbital analyses on the observed [U(CN)(NH3)8]3+ cation and the [(μ-CN)2{(H3N)5U(μ-NH2)3U(NH3)5}]3+ model cation to gain insight into the bonding situation.