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.

2024, Shen, Xingchen, Ouyang, Niuchang, Huang, Yuling, Tung, Yung‐Hsiang, Yang, Chun‐Chuen, Faizan, Muhammad, Perez, Nicolas, He, Ran, Sotnikov, Andrei, Willa, Kristin, Wang, Chen, Chen, Yue, Guilmeau, Emmanuel

Due to their amorphous-like ultralow lattice thermal conductivity both below and above the superionic phase transition, crystalline Cu- and Ag-based superionic argyrodites have garnered widespread attention as promising thermoelectric materials. However, despite their intriguing properties, quantifying their lattice thermal conductivities and a comprehensive understanding of the microscopic dynamics that drive these extraordinary properties are still lacking. Here, an integrated experimental and theoretical approach is adopted to reveal the presence of Cu-dominated low-energy optical phonons in the Cu-based argyrodite Cu7PS6. These phonons yield strong acoustic-optical phonon scattering through avoided crossing, enabling ultralow lattice thermal conductivity. The Unified Theory of thermal transport is employed to analyze heat conduction and successfully reproduce the experimental amorphous-like ultralow lattice thermal conductivities, ranging from 0.43 to 0.58 W m−1 K−1, in the temperature range of 100–400 K. The study reveals that the amorphous-like ultralow thermal conductivity of Cu7PS6 stems from a significantly dominant wave-like conduction mechanism. Moreover, the simulations elucidate the wave-like thermal transport mainly results from the contribution of Cu-associated low-energy overlapping optical phonons. This study highlights the crucial role of low-energy and overlapping optical modes in facilitating amorphous-like ultralow thermal transport, providing a thorough understanding of the underlying complex dynamics of argyrodites.

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.

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

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.

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.

2024, Roslova, Maria, Büchner, Bernd, Maljuk, Andrey

In this review, we summarize recent progress in crystal growth and understanding of the influence of crystal structure on superconductivity in pure and Pb-doped Bi2Sr2CuOy (Bi-2201) materials belonging to the overdoped region of high-temperature cuprate superconductors. The crystal growth of Bi-2201 superconductors faces challenges due to intricate materials chemistry and the lack of knowledge of corresponding phase diagrams. Historically, a crucible-free floating zone method emerged as the most promising growth approach for these materials, resulting in high-quality single crystals. This review outlines the described methods in the literature and the authors’ synthesis endeavors encompassing Pb-doped Bi-2201 crystals, provides a detailed structural characterization of as-grown and post-growth annealed samples, and highlights optimal growth conditions that yield large-size, single-phase, and compositionally homogeneous Bi-2201 single crystals.

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.

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).

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.