Search Results
Crystal structure of diethyl (E)-2-[(benzofuran-2-yl)methylidene]succinate
2015, Schirmer, Marie-Luis, Spannenberg, Anke, Werner, Thomas
The title compound, C17H18O5, was synthesized by a base-free catalytic Wittig reaction. The molecule consists of a diethyl itaconate unit, which is connected via the C=C double bond to a benzofuran moiety. The benzofuran ring system (r.m.s. deviation = 0.007 Å) forms dihedral angles of 79.58 (4) and 12.12 (10)° with the mean planes through the cis and trans ethoxycarbonyl groups, respectively. An intramolecular C-H...O hydrogen bond involving the O atom of the benzofuran moiety is observed. In the crystal, molecules are linked into ribbons running parallel to the b axis by C-H...O hydrogen bonds.
Crystal structure of 1,1,2,2-tetramethyl-1,2-bis(2,3,4,5-tetramethylcyclopenta-2,4-dien-1-yl)disilane
2015, Godemann,Christian, Spannenberg, Anke, Beweries, Torsten
The molecular structure of the title compound, C22H38Si2, features a trans arrangement of the cyclopentadienyl rings to avoid steric strain [C-Si-Si-C torsion angle = -179.0 (5)°]. The Si-Si bond length is 2.3444 (4) Å. The most notable intermolecular interactions in the molecular packing are C-H...[pi] contacts that lead to the formation of wave-like supramolecular chains along the b axis.
Enantio- and diastereoselective synthesis of γ-amino alcohols
2015, Verkade, Jorge M. M., Quaedflieg, Peter J. L. M., Verzijl, Gerard K. M., Lefort, Laurent, van Delft, Floris L., de Vries, Johannes G., Rutjes, Floris P. J. T.
The γ-amino alcohol structural motif is often encountered in drugs and natural products. We developed two complementary catalytic diastereoselective methods for the synthesis of N-PMP-protected γ-amino alcohols from the corresponding ketones. The anti-products were obtained through Ir-catalyzed asymmetric transfer hydrogenation, the syn-products via Rh-catalyzed asymmetric hydrogenation.
Tetracarbonyl-2κ4C-[μ-5-methyl-1,1,3-triphenyl-2-(propan-2-yl)-2,4-diaza-1,3-diphosphahexan-4-ido-1κN4:2κP1,P3](N,N,N′,N′-tetramethylethane-1,2-diamine-1κ2N,N′)lithiummolybdenum
2018, Höhne, Martha, Spannenberg, Anke, Müller, Bernd H., Peulecke, Normen, Rosenthal, Uwe
The title complex, [LiMo(C6H16N2)(C24H29N2P2)(CO)4], contains a distorted octahedrally coordinated molybdenum centre bearing a lithiated P,P′-cis-chelating PNPN ligand, which results in a nearly planar four-membered metallacycle. The Li atom is coordinated by one equivalent tetramethylethylenediamine. In the crystal, molecules are linked via weak C—H...O interactions, forming a chain along the b-axis direction.
Crystal structure of bis{μ2-[(2-iminocyclopentylidene)methylidene]azanido-κ2 N:N'}bis[(η5-pentamethylcyclopentadienyl)zirconium(IV)] hexane monosolvate
2015, Becker, Lisanne, Spannenberg, Anke, Arndt, Perdita, Rosenthal, Uwe
The title compound, [Zr2(C10H15)4(C6H6N2)2]·C6H14, was obtained by the stoichiometric reaction of adiponitrile with [Zr(C10H15)2([eta]2-Me3SiC2SiMe3)]. Intramolecular nitrile-nitrile couplings and deprotonation of the substrate produced the (1-imino-2-enimino)cyclopentane ligand, which functions as a five-membered bridge between the two metal atoms. The ZrIV atom exhibits a distorted tetrahedral coordination sphere defined by two pentamethylcyclopentadienyl ligands, by the imino unit of one (1-imino-2-enimino)cyclopentane and by the enimino unit of the second (1-imino-2-enimino)cyclopentane. The cyclopentane ring of the ligand shows an envelope conformation. The asymmetric unit contains one half of the complex and one half of the hexane solvent molecule, both being completed by the application of inversion symmetry. One of the pentamethylcyclopentadienyl ligands is disordered over two sets of sites with a refined occupancy ratio of 0.8111 (3):0.189 (3). In the crystal, the complex molecules are packed into rods extending along [100], with the solvent molecules located in between. The rods are arranged in a distorted hexagonal packing.
Synthesis and crystallographic characterization of [2,2-bis(η5-pentamethylcyclopentadienyl)-3,4-bis(trimethylsilyl)-2-zirconafuran-5-one-κO5]triisobutylaluminium
2018-3-27, Burlakov, Vladimir V., Bogdanov, Vyacheslav S., Arndt, Perdita, Spannenberg, Anke, Rosenthal, Uwe, Beweries, Torsten, Shur, Vladimir B.
The crystal structure of the title zwitterionic zirconocene complex containing a furanone unit, [AlZr(C10H15)2(C4H9)3(C9H18O2Si2)], is reported. On reacting a zirconafuranone with two equivalents of HAl(i-Bu)2, disproportionation of the Lewis acid results in the formation of a triisobutylaluminium fragment, Al(i-Bu)3, which coordinates to the exocyclic carbonyl O atom of the zirconafuranone ring. Single-crystal X-ray diffraction reveals that the zirconafuranone ring remains intact with coordination of the aluminium to the exocyclic O atom. One of the i-butyl groups is disordered over two sets of sites, with an occupancy ratio of 0.731 (3):0.269 (3).
The Weak 3D Topological Insulator Bi12Rh3Sn3I9
2020, Lê Anh, Mai, Kaiser, Martin, Ghimire, Madhav Prasad, Richter, Manuel, Koepernik, Klaus, Gruschwitz, Markus, Tegenkamp, Christoph, Doert, Thomas, Ruck, Michael
Topological insulators (TIs) gained high interest due to their protected electronic surface states that allow dissipation-free electron and information transport. In consequence, TIs are recommended as materials for spintronics and quantum computing. Yet, the number of well-characterized TIs is rather limited. To contribute to this field of research, we focused on new bismuth-based subiodides and recently succeeded in synthesizing a new compound Bi12Rh3Sn3I9, which is structurally closely related to Bi14Rh3I9 – a stable, layered material. In fact, Bi14Rh3I9 is the first experimentally supported weak 3D TI. Both structures are composed of well-defined intermetallic layers of ∞2[(Bi4Rh)3I]2+ with topologically protected electronic edge-states. The fundamental difference between Bi14Rh3I9 and Bi12Rh3Sn3I9 lies in the composition and the arrangement of the anionic spacer. While the intermetallic 2D TI layers in Bi14Rh3I9 are isolated by ∞1[Bi2I8]2− chains, the isoelectronic substitution of bismuth(III) with tin(II) leads to ∞2[Sn3I8]2− layers as anionic spacers. First transport experiments support the 2D character of this material class and revealed metallic conductivity. © 2020 The Authors. Published by Wiley-VCH GmbH
Crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand
2016, Kessler, Monty, Godemann, Christian, Spannenberg, Anke, Beweries, Torsten
The crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand are reported, namely [di-methylbis-(η5-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κ2O,O')titanium(III) toluene monosolvate, [Ti(CF3O3S)(C20H30Si)]·C7H8, 1, and chlorido-[di-methyl-bis-(η5-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κO)titanium(IV), [Ti(CF3O3S)(C20H30Si)Cl], 2. Both complexes display a bent metallocene unit, the metal atom being coordinated in a distorted tetra-hedral geometry, with the tri-fluoro-methane-sulfonate anion acting as a bidentate or monodentate ligand in 1 and 2, respectively. In 1, weak π-π stacking inter-actions involving the toluene solvent mol-ecules [centroid-to-centroid distance = 3.9491 (11) Å] are observed.
Crystal structure of 1-hydroxy-2,2,6,6-tetramethylpiperidin-1-ium trifluoromethanesulfonate
2015, Godemann,Christian, Spannenberg, Anke, Beweries, Torsten
In the cation of the title salt, C9H20NO+·CF3O3S-, the six-membered heterocyclic ring displays a chair conformation. In the crystal, centrosymmetric pairs of cations and anions are linked by N-H...O and O-H...O hydrogen bonds to form rings with a R44(14) graph-set motif.
The Contrasting Character of Early and Late Transition Metal Fluorides as Hydrogen Bond Acceptors
2015, Smith, Dan A., Beweries, Torsten, Blasius, Clemens, Jasim, Naseralla, Nazir, Ruqia, Nazir, Sadia, Robertson, Craig C., Whitwood, Adrian C., Hunter, Christopher A., Brammer, Lee, Perutz, Robin N.
The association constants and enthalpies for the binding of hydrogen bond donors to group 10 transition metal complexes featuring a single fluoride ligand (trans-[Ni(F)(2-C5NF4)(PR3)2], R = Et 1a, Cy 1b, trans-[Pd(F)(4-C5NF4)(PCy3)2] 2, trans-[Pt(F){2-C5NF2H(CF3)}(PCy3)2] 3 and of group 4 difluorides (Cp2MF2, M = Ti 4a, Zr 5a, Hf 6a; Cp*2MF2, M = Ti 4b, Zr 5b, Hf 6b) are reported. These measurements allow placement of these fluoride ligands on the scales of organic H-bond acceptor strength. The H-bond acceptor capability β (Hunter scale) for the group 10 metal fluorides is far greater (1a 12.1, 1b 9.7, 2 11.6, 3 11.0) than that for group 4 metal fluorides (4a 5.8, 5a 4.7, 6a 4.7, 4b 6.9, 5b 5.6, 6b 5.4), demonstrating that the group 10 fluorides are comparable to the strongest organic H-bond acceptors, such as Me3NO, whereas group 4 fluorides fall in the same range as N-bases aniline through pyridine. Additionally, the measurement of the binding enthalpy of 4-fluorophenol to 1a in carbon tetrachloride (−23.5 ± 0.3 kJ mol–1) interlocks our study with Laurence’s scale of H-bond basicity of organic molecules. The much greater polarity of group 10 metal fluorides than that of the group 4 metal fluorides is consistent with the importance of pπ–dπ bonding in the latter. The polarity of the group 10 metal fluorides indicates their potential as building blocks for hydrogen-bonded assemblies. The synthesis of trans-[Ni(F){2-C5NF3(NH2)}(PEt3)2], which exhibits an extended chain structure assembled by hydrogen bonds between the amine and metal-fluoride groups, confirms this hypothesis.