Sr(Hg1–xSnx)4: variations of the EuIn4-type structure

2015 ◽  
Vol 70 (4) ◽  
pp. 265-277
Author(s):  
Marco Wendorff ◽  
Caroline Röhr
Keyword(s):  
Density Functional ◽  
Valence Electron ◽  
Theoretical Study ◽  
Building Blocks ◽  
Type Structure ◽  
Intermediate Valence ◽  
Model Compounds ◽  
Functional Theory ◽  
X Ray ◽  
Successive Substitution

AbstractStarting from the new compound SrHg2Sn2, which is isoelectronic and also isotypic to the indide SrIn4, the successive substitution of Sn against the electron poor Hg has been investigated in a combined synthetic, crystallographic, and bond-theoretical study. Along the 1:4 section Sr(Hg1–xSnx)4 a series of compounds with Sn contents x between 0.5 and 0.2 were synthesized from stoichiometric ratios of the elements. Their crystal structures, which represent three different variants of the EuIn4-type structure, have been determined using single crystal X-ray data. The most electron rich compound SrHg2Sn2 crystallizes in the original EuIn4-type [monoclinic, C2/m, a = 1257.9(14), b = 490.1(4), c = 997.8(12) pm, β = 117.60(6)°, Z = 4, R1 = 0.0838], with a fully ordered Hg and Sn distribution. The four atom sites form two different folded ladders with an alternating Hg/Sn distribution. Like in the KHg2-type, the ladders are connected via six-membered rings. In between, double tubes with an internal Sn–Sn bond are connected via further Sn–Sn bonds to form sheets similar to those observed in SiAs. The most electron-poor phase SrHg3.2Sn0.8 crystallizes in a strongly distorted variant of this structure [a = 1172.8(4), b = 497.9(2), c = 1010.0(4) pm, β = 118.860(7)°, Z = 4, R1 = 0.0549]. Herein, additional Hg–Hg bonds are formed, and the open tubes are distorted into rods of edge-sharing rhombohedra resembling the structure motifs of elemental Hg. At an intermediate valence electron (v.e.) number, i.e., in SrHg2.5Sn1.5, an isomorphous tripled superstructure (a = 2704.4(5), b = 493.87(7), c = 1197.1(2) pm, β = 90.838(14)°, Z = 12, R1 = 0.0475) occurs, where the building blocks of the two variants of the EuIn4-type structure alternate in a 1:2 ratio. The bonding situation and the “coloring,” i.e., the Hg/Sn distribution in the polyanionic network, are discussed considering the different sizes of the atoms and the charge distribution (Bader AIM charges), which has been calculated within the framework of the FP-LAPW density functional theory for SrHg2Sn2 and the model compounds “SrHg3Sn” and “SrHg4.”

Different Cerium Valence Transitions Observed by Hydrogenation of the Ternary Germanides CeRhGe and CeIrGe – Structure, Physical Properties and Chemical Bonding

2008 ◽  
Vol 63 (6) ◽  
pp. 685-694 ◽  
Author(s):  
Bernard Chevalier ◽  
Etienne Gaudin ◽  
Adel F. Al Alam ◽  
Samir F. Matar ◽  
François Weill ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Spin Fluctuation ◽  
Type Structure ◽  
Kondo Temperature ◽  
Intermediate Valence ◽  
Functional Theory ◽  
X Ray ◽  
Transmission Electron ◽  
Power Measurements

The ternary germanides CeRhGe and CeIrGe which crystallize in the orthorhombic TiNiSi-type structure, absorb hydrogen at 523 K. X-Ray powder diffraction and transmission electron microscopy indicate that the hydrides CeRhGeH1.8 and CeIrGeH1.8 adopt the hexagonal ZrBeSi-type structure. Magnetization, electrical resistivity and thermoelectric power measurements reveal that these hydrides are intermediate-valence compounds. An unusual transition from antiferromagnetic to spin fluctuation behavior occurs upon hydrogenation of CeRhGe, while on the contrary, CeIrGeH1.8 presents a Kondo temperature of 285 K smaller than that observed for CeIrGe (610 K). In order to explain these opposite valence transitions, the electronic structures of the hydrides have been selfconsistently calculated within the local spin density functional theory (LSDF). The structures are compared to those reported previously by us for CeRhGe and CeIrGe.

scholarly journals Size Matters: New Zintl Phase Hydrides of REGa (RE = Y, La, Tm) and RESi (RE = Y, Er, Tm) with Large and Small Cations

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 600
Author(s):  
Werwein ◽  
Hansen ◽  
Kohlmann
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Structural Diversity ◽  
Type Structure ◽  
Zintl Phases ◽  
Structure Form ◽  
Functional Theory ◽  
X Ray ◽  
Hydrogenation Reactions ◽  
Tetrahedral Voids

Many Zintl phases exhibiting a CrB type structure form hydrides. Systematic studies of AeTtHx (Ae = Ca, Sr, Ba; Tt = Si, Ge, Sn), LnTtHx (Ln = La, Nd; Tt = Si, Ge, Sn), and LnGaHx (Ln = Nd, Gd) showed the vast structural diversity of these systems. Hydrogenation reactions on REGa (RE = Y, La, Tm) and RESi (RE = Y, Er, Tm) were performed in steel autoclaves under hydrogen pressure up to 5 MPa and temperatures up to 773 K. The products were analyzed by X-ray and neutron powder diffraction. RESi (RE = Y, Er, Tm) form hydrides in the C-LaGeD type. LaGaD1.66 is isostructural to NdGaD1.66 and shows similar electronic features. Ga-D distances (1.987(13) Å and 2.396(9) Å) are considerably longer than in polyanionic hydrides and not indicative of covalent bonding. In TmGaD0.93(2) with a distorted CrB type structure deuterium atoms exclusively occupy tetrahedral voids. Theoretical calculations on density functional theory (DFT) level confirm experimental results and suggest metallic properties for the hydrides.

A new ZnII metallocryptand with unprecedented diflexure helix induced by V-shaped diimidazole building blocks

2020 ◽  
Vol 76 (3) ◽  
pp. 411-416
Author(s):  
Zhi-Qiang Shi ◽  
Ning-Ning Ji ◽  
Hai-Liang Hu
Keyword(s):  
Density Functional ◽  
Building Blocks ◽  
Isophthalic Acid ◽  
Helical Chain ◽  
Zigzag Chain ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Fluorescence Measurements ◽  
Ligand Charge Transfer

Taking advantage of V-shaped ligands, a ZnII metallocryptand, namely {[Zn2(didp)2(m-bdc)2]} n , (1) [didp = 2,8-di(1H-imidazol-1-yl)-dibenzothiophene and m-H2bdc = isophthalic acid], has been hydrothermally synthesized. Single-crystal X-ray diffraction analysis reveals a 26-membered butterfly-type metallomacrocycle [Zn2(didp)2]. One m-bdc2− ligand bridges [Zn2(didp)2] units to form a laterally non-symmetric [Zn2(didp)2(m-bdc)] metallocryptand with an exo–exo conformation. Another crystallographically independent m-bdc2− functions as a secondary synthon to bridge discrete metallocryptands into a 1D zigzag chain architecture. Undoubtedly, the choice of two matched ligands in this work is crucial for metallocryptand construction and structure expansion. Interestingly, a rare helical chain with two flexures in one single L and/or R strand is observed. Another important feature is the C—O...π interactions, by which the dimensionality extension of (1) can be induced. Fluorescence measurements and density functional theory (DFT) calculations illustrate that the emission of (1) can probably be attributed to ligand-to-ligand charge transfer (LLCT).

Probing non-covalent interactions driving molecular assembly in organo-electronic building blocks

CrystEngComm ◽  
2019 ◽  
Vol 21 (20) ◽  
pp. 3151-3157 ◽  
Author(s):  
Sarah N. Johnson ◽  
Thomas L. Ellington ◽  
Duong T. Ngo ◽  
Jorge L. Nevarez ◽  
Nicholas Sparks ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Building Blocks ◽  
Molecular Assembly ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Non Covalent Interactions ◽  
Density Functional Theory Computations ◽  
Covalent Interactions

One co-crystal structure characterized to identify and quantify various non-covalent interactions with spectroscopy, X-ray crystallography and density functional theory computations.

scholarly journals Neutral Rhenadicarbaboranes with Re(CO)2(NO) Vertices: A Theoretical Study of Building Blocks for Rhenacarborane-Based Drug Delivery Agents

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 110 ◽  
Author(s):  
Amr A. A. Attia ◽  
Alexandru Lupan ◽  
Radu Silaghi-Dumitrescu ◽  
R. Bruce King
Keyword(s):  
Drug Delivery ◽  
Density Functional Theory ◽  
Carbon Atom ◽  
Related Species ◽  
Density Functional ◽  
Theoretical Study ◽  
Building Blocks ◽  
Rhenium Atom ◽  
Functional Theory

The rhenadicarbaborane carbonyl nitrosyls (C2Bn−3Hn−1)Re(CO)2(NO), (n = 8 to 12), of interest in drug delivery agents based on the experimentally known C2B9H11Re(CO)2(NO) and related species, have been investigated by density functional theory. The lowest energy structures of these rhenadicarbaboranes are all found to have central ReC2Bn−3 most spherical closo deltahedra in accord with their 2n + 2 Wadean skeletal electrons. Carbon atoms are found to be located preferentially at degree 4 vertices in such structures. Furthermore, rhenium atoms are preferentially located at a highest degree vertex, typically a vertex of degree 5. Only for the 9-vertex C2B6H8Re(CO)2(NO) system are alternative isocloso deltahedral isomers found within ~8 kcal/mol of the lowest energy closo isomer. Such 9-vertex isocloso structures provide a degree 6 vertex for the rhenium atom flanked by degree 4 vertices for each carbon atom.

scholarly journals The structure of ortho-(trifluoromethyl)phenol in comparison to its homologues – A combined experimental and theoretical study

2018 ◽  
Vol 16 (1) ◽  
pp. 745-756
Author(s):  
Richard Betz
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Theoretical Study ◽  
Functional Theory ◽  
X Ray ◽  
Iodine Compounds ◽  
Natural Bonding Orbital ◽  
Ft Ir ◽  
Reactions With Nucleophiles

AbstractThe molecular and crystal structure of commercially-availableortho-(trifluoromethyl)phenol were determined by means of single-crystal X-ray diffractometry (XRD) and represent the first structural characterization of anortho-substituted (trihalomethyl) phenol. The unexpected presence of a defined hydrate in the solid state was observed.Intermolecular contacts and hydrogen bonding were analyzed. The compound was further characterized by means of multi-nuclear nuclear magnetic resonance (NMR) spectroscopy (1H,13C{1H},19F) and Fourier-Transform infrared (FT-IR) vibrational spectroscopy. To assess the bonding situation as well as potential reaction sites for reactions with nucleophiles and electrophiles in the compound by means of natural bonding orbital (NBO) analyses, and density functional theory (DFT) calculations were performed for the title compound as well as its homologous chlorine, bromine and iodine compounds. As far as possible, experimental data were correlated to DFT data.

Crystal structure and theoretical investigation of bis(cis-1,2-diaminocyclohexane)zinc(II) tetrachloridozincate(II)

2017 ◽  
Vol 72 (8) ◽  
pp. 627-630 ◽  
Author(s):  
Muhammad Akhtar ◽  
Wiktor Zierkiewicz ◽  
Mariusz Michalczyk ◽  
Tobias Rüffer ◽  
Heinrich Lang ◽  
...  
Keyword(s):  
Density Functional ◽  
Tetrahedral Coordination ◽  
Cationic Complex ◽  
Model Compounds ◽  
Tetrahedral Geometry ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrogen Bonding Interactions ◽  
Dimensional Network

AbstractA zinc(II) complex of cis-1,2-diaminocyclohexane (Dach), [Zn(Dach)2][ZnCl4] (1), was prepared and its structure was determined by X-ray crystallography. Theoretical (density functional theory) studies were performed for the two model compounds, [Zn(Dach)2][ZnCl4] (1) and {[Zn(Dach)2][ZnCl4]}3 (13). The structure of complex 1 is composed of [Zn(Dach)2]2+ cations and [ZnCl4]2− anions. The Zn1 atom in the cationic complex adopts a severely distorted tetrahedral geometry, while in the anionic part, Zn2 displays only a slight distortion from tetrahedral coordination. The adjacent cations and anions are associated with each other through hydrogen bonding interactions to form a two-dimensional network in the solid state.

scholarly journals Quantum chemical study of electron structure and charge transport properties of symmetric acenequinones

2018 ◽  
Vol 11 (2) ◽  
pp. 83-93
Author(s):  
Denisa Cagardová ◽  
Martin Michalík ◽  
Peter Poliak ◽  
Vladimír Lukeš
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Organic N ◽  
Semiconducting Materials ◽  
Functional Theory ◽  
X Ray ◽  
Different Types ◽  
Lowest Unoccupied Molecular Orbital

Abstract A systematic theoretical study using density functional theory is presented to estimate the structural, electronic, and charge-transfer characteristics of a symmetric fluorination of acenequinones outer rings. The change in aromaticity of model derivatives was described by different types of aromaticity indices. By considering a hopping mechanism and using the Marcus theory in combination with the Einstein-Smoluchowski relation, electronic drift mobilities were predicted for selected dimer configurations obtained from X-ray structures of anthraquinone, 6,13-pentacenequinone and its octafluorinated derivatives. The analysis of obtained data showed that the fluorination of the outer rings of acenequinones can lower the energy of the lowest unoccupied molecular orbital to the range from −3.0 to −4.0 eV, i.e. typical for organic n-type semiconducting materials. Finally, potential electric semiconductivity of available X-ray structures relating to drift mobilities was discussed.

Evolution of CH3NO2/Si interfacial chemistry under reaction conditions: a combined experimental and theoretical study

2017 ◽  
Vol 53 (23) ◽  
pp. 3342-3345 ◽  
Author(s):  
Xueqiang Zhang ◽  
Chen-Guang Wang ◽  
Wei Ji ◽  
Sylwia Ptasinska
Keyword(s):  
Density Functional Theory ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Theoretical Study ◽  
Ambient Pressure ◽  
Dissociative Adsorption ◽  
Interfacial Chemistry ◽  
Reaction Conditions ◽  
Functional Theory ◽  
X Ray

Dissociative adsorption of CH3NO2 onto a Si(100)-2 × 1 surface is studied using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and density functional theory (DFT) calculations.

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