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Keywords = electron localizability

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13 pages, 4136 KB  
Article
Polycation–Polyanion Architecture of the Intermetallic Compound Mg3−xGa1+xIr
by Olga Sichevych, Yurii Prots, Walter Schnelle, Frank R. Wagner and Yuri Grin
Molecules 2022, 27(3), 659; https://doi.org/10.3390/molecules27030659 - 20 Jan 2022
Cited by 12 | Viewed by 3248
Abstract
Mg3−xGa1+xIr (x = 0.05) was synthesized by direct reaction of the elements in welded tantalum containers at 1200 °C and subsequent annealing at 500 °C for 30 days. Its crystal structure represents a new prototype and [...] Read more.
Mg3−xGa1+xIr (x = 0.05) was synthesized by direct reaction of the elements in welded tantalum containers at 1200 °C and subsequent annealing at 500 °C for 30 days. Its crystal structure represents a new prototype and was determined by single-crystal technique as follows: space group P63/mcm, Pearson symbol hP90, Z = 18, a = 14.4970(3) Å, c = 8.8638(3) Å. The composition and atomic arrangement in Mg3GaIr do not follow the 8–N rule due to the lack of valence electrons. Based on chemical bonding analysis in positional space, it was shown that the title compound has a polycationic–polyanionic organization. In comparison with other known intermetallic substances with this kind of bonding pattern, both the polyanion and the polyanion are remarkably complex. Mg3−xGa1+xIr is an example of how the general organization of intermetallic substances (e.g., formation of polyanions and polycations) can be understood by extending the principles of 8–N compounds to electron-deficient materials with multi-atomic bonding. Full article
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12 pages, 7787 KB  
Article
High-Pressure Modification of BiI3
by Ulrich Schwarz, Aron Wosylus, Marcus Schmidt, Lev Akselrud, Alim Ormeci, Michael Hanfland, Volker Hermann and Christine Kuntscher
Inorganics 2019, 7(12), 143; https://doi.org/10.3390/inorganics7120143 - 13 Dec 2019
Cited by 8 | Viewed by 4331
Abstract
Structural and optical properties as well as chemical bonding of BiI3 at elevated pressures are investigated by means of refinements of X-ray powder diffraction data, measurements of the optical absorption, and calculations of the band structure involving bonding analysis in real space. [...] Read more.
Structural and optical properties as well as chemical bonding of BiI3 at elevated pressures are investigated by means of refinements of X-ray powder diffraction data, measurements of the optical absorption, and calculations of the band structure involving bonding analysis in real space. The data evidence the onset of a phase transition from trigonal (hR24) BiI3 into PuBr3-type (oS16) BiI3 around 4.6 GPa. This high-pressure modification remains stable up to 40 GPa, the highest pressure of this study. The phase exhibits semiconducting properties with constantly decreasing band gap between 5 and 18 GPa. Above this pressure, the absorbance edge broadens significantly. Extrapolation of the determined band gap values implies a semiconductor to metal transition at approximately 35 GPa. The value is in accordance with subtle structural anomalies and the results of band structure calculations. Topological analysis of the computed electron density and the electron-localizability indicator reveal fingerprints for weak covalent Bi-I contributions in addition to dominating ionic interactions for both modifications. Full article
(This article belongs to the Special Issue Structure, Properties, and Bonding in Solid State Compounds)
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11 pages, 3234 KB  
Article
Atomic Charges and Chemical Bonding in Y-Ga Compounds
by Yuri Grin, Anatolij Fedorchuk, Rodolfo J. Faria and Frank R. Wagner
Crystals 2018, 8(2), 99; https://doi.org/10.3390/cryst8020099 - 16 Feb 2018
Cited by 16 | Viewed by 5498
Abstract
A negative deviation from Vegard rule for the average atomic volume versus yttrium content was found from experimental crystallographic information about the binary compounds of yttrium with gallium. Analysis of the electron density (DFT calculations) employing the quantum theory of atoms in molecules [...] Read more.
A negative deviation from Vegard rule for the average atomic volume versus yttrium content was found from experimental crystallographic information about the binary compounds of yttrium with gallium. Analysis of the electron density (DFT calculations) employing the quantum theory of atoms in molecules revealed an increase in the atomic volumes of both Y and Ga with the increase in yttrium content. The non-linear increase is caused by the strengthening of covalent Y-Ga interactions with stronger participation of genuine penultimate shell electrons (4d electrons of yttrium) in the valence region. Summing the calculated individual atomic volumes for a unit cell allows understanding of the experimental trend. With increasing yttrium content, the polarity of the Y-Ga bonding and, thus its ionicity, rises. The covalency of the atomic interactions in Y-Ga compounds is consistent with their delocalization from two-center to multi-center ones. Full article
(This article belongs to the Special Issue Experimental and Theoretical Electron Density Analysis of Crystals)
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17 pages, 2183 KB  
Article
New Look on 3-Hydroxyiminoflavanone and Its Palladium(II) Complex: Crystallographic and Spectroscopic Studies, Theoretical Calculations and Cytotoxic Activity
by Maria Kasprzak, Małgorzata Fabijańska, Lilianna Chęcińska, Leszek Szmigiero and Justyn Ochocki
Molecules 2016, 21(4), 455; https://doi.org/10.3390/molecules21040455 - 13 Apr 2016
Cited by 5 | Viewed by 5605
Abstract
This work presents the synthesis, spectroscopic properties and single-crystal X-ray examination of the structure of 3-hydroxyiminoflavanone and its palladium complex. It presents the results of NMR (Nuclear Magnetic Resonance) spectroscopy, electron-density studies based on X-ray wavefunction refinement and theoretical calculations combined with QTAIM [...] Read more.
This work presents the synthesis, spectroscopic properties and single-crystal X-ray examination of the structure of 3-hydroxyiminoflavanone and its palladium complex. It presents the results of NMR (Nuclear Magnetic Resonance) spectroscopy, electron-density studies based on X-ray wavefunction refinement and theoretical calculations combined with QTAIM (Quantum Theory of Atoms in Molecules) and ELI-D (Electron Localizability Indicator) analyses. These offer an interesting new insight into the structures and behavior of flavanone and its complex, in solid state and in solution. The study also examines the cytotoxicity of the ligand and its complex against three human ovarian and lung cancer cell lines. Full article
(This article belongs to the Section Organometallic Chemistry)
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