- Li7Cd4.5Ge4Se16 and Li6.4Cd4.8Sn4Se16: Strong Nonlinear Optical Response in Quaternary Diamond-Like Selenide Networks
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Two new selenides with diamond-like structures, Li7Cd4.5Ge4Se16 and Li6.4Cd4.8Sn4Se16, were synthesized by using a conventional high-temperature solid-state reaction m
- Guo, Yangwu,Li, Xiaoshuang,Feng, Kai,Li, Chao,Zhou, Molin,Wu, Yicheng,Yao, Jiyong
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- Organosilicon chalcogenides with trisilane units - Bicyclo[3.3.1]nonanes, bicyclo[3.2.2]nonanes and spiro[4.4]nonanes
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Treatment of 1,2,3-trichloropentamethyltrisilane (1) with H2S/NEt3 results in the formation of a mixture of two isomers of (Me5Si3)2 S3 with a bicyclo[3.3.1]nonane (2a) and a bicyclo[3.2.2]nonane (2b) skeleton, while the reaction of 1 with Li2Se yields one product only, (Me5 Si3)2Se3 (3a), with a bicyclo[3.3.1]nonane structure. Besides 1H, 13C, 29Si and 77Se NMR spectroscopy 3a has also been characterized by a crystal structure analysis. Compounds Si(SiMe2EMR2E)2 (5a-h: MR2: SiMe2 (5a, c, d), SiPh2 (5b), GeMe2 (5e, f), SnMe2 (5g, h); E=S (5a, b, e, g), Se (5c, f, h), Te (5d)) with a spiro[4.4]nonane skeleton have been obtained in mixture with varying amounts of the corresponding six-membered rings (R2ME)3 by reactions of mixtures of 1,2,2,3-tetrachlorotetramethyltrisilane (4) and diorganodichlorosilanes, Me2GeCl2 or Me2SnCl2, with H2S/NEt3, Li2Se or Li2Te and have been characterized in situ by multinuclear NMR spectroscopy (1H, 13C, 29Si, 119Sn, 77Se, 125Te) and GC-MS.
- Herzog, Uwe,Borrmann
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- Two-Dimensional Substitution: Toward a Better Understanding of the Structure-Transport Correlations in the Li-Superionic Thio-LISICONs
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A deeper understanding of the relationships among composition-structure-transport properties in inorganic solid ionic conductors is of paramount importance to develop highly conductive phases for future employment in solid-state Li-ion battery applications. To shed light on the mechanisms that regulate these relationships, in this work, we perform a two-dimensional substitution series in the thio-LISICON family Li4Ge1-xSnxS4-ySey. The structural modifications brought up by the elemental substitutions were investigated via Rietveld refinements against high-resolution neutron diffraction data that allowed a precise characterization of the anionic framework and lithium substructure. The analyses show that the anionic and cationic substitutions influence the polyhedral and unit cell volumes in different fashions and that the size of the polyanionic groups alone is not enough to describe lattice expansion in these materials. Moreover, we show that the lithium disorder that is crucial to achieve fast ionic mobility may be correlated to the lithium polyhedral volumes. The correlation of these structural modifications with the transport properties, investigated via electrochemical impedance spectroscopy and 7Li nuclear magnetic resonance spin-lattice relaxation measurements, shows a nonmonotonic behavior of the ionic conductivity and activation energy against the lithium polyhedral volumes, hinting to an optimal size of the conduction pathways for the ionic diffusion. Ultimately, the results obtained in this work will help to establish new guidelines for the optimization of solid electrolytes and gain a more profound understanding of the influence of the substituents on the structure and transport properties of Li-ion conductors.
- Minafra, Nicolò,Hogrefe, Katharina,Barbon, Federico,Helm, Bianca,Li, Cheng,Wilkening, H. Martin R.,Zeier, Wolfgang G.
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- Room-temperature synthesis, hydrothermal recrystallization, and properties of metastable stoichiometric FeSe
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Room-temperature precipitation from aqueous solutions yields the hitherto unknown metastable stoichiometric iron selenide (ms-FeSe) with tetragonal anti-PbO type structure. Samples with improved crystallinity are obtained by diffusion-controlled precipitation or hydrothermal recrystallization. The relations of ms-FeSe to superconducting η-FeSe1-x and other neighbor phases of the iron-selenium system are established by high-temperature X-ray diffraction, DSC/TG/MS (differential scanning calorimetry/ thermogravimetry/mass spectroscopy), 57Fe Moessbauer spectroscopy, magnetization measurements, and transmission electron microscopy. Above 300 °C, ms-FeSe decomposes irreversibly to η-FeSe1-x and Fe7Se8. The structural parameters of ms-FeSe (P4/nmm, a = 377.90(1) pm, c = 551.11(3) pm, Z = 2), obtained by Rietveld refinement, differ significantly from literature data for η-FeSe1-x. The Moessbauer spectrum rules out interstitial iron atoms or additional phases. Magnetization data suggest canted antiferromagnetism below TN = 50 K. Stoichiometric non-superconducting ms-FeSe can be regarded as the true parent compound for the 11 iron-chalcogenide superconductors and may serve as starting point for new chemical modifications.
- Nitsche,Goltz,Klauss,Isaeva,Mueller,Schnelle,Simon,Doert, Th.,Ruck
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- Cyclic Silylselenides: Convenient Selenium Precursors for Atomic Layer Deposition
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Three cyclic silylselenides were prepared in a straightforward manner. Property tuning has been achieved by varying the ring size and the number of embedded selenium atoms. All silylselenides possess improved resistance towards moisture and oxidation as well as high thermal robustness and sufficient volatility with almost zero residues. The six-membered diselenide proved to be particularly superior Se precursors for atomic layer deposition and allowed facile preparation of MoSe2 layers. Their structure and composition have been investigated by Raman and X-ray photoelectron spectroscopy as well as scanning electron microscopy revealing vertically aligned flaky shaped nanosheets.
- Charvot, Jaroslav,Pokorny, Daniel,Zazpe, Raul,Krumpolec, Richard,Pavliňák, David,Hromádko, Luděk,P?ikryl, Jan,Rodriguez-Pereira, Jhonatan,Klikar, Milan,Jelínková, Veronika,Macak, Jan M.,Bure?, Filip
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- Deposition of MoSe2flakes using cyclic selenides
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The currently limited portfolio of volatile organoselenium compounds used for atomic layer deposition (ALD) has been extended by designing and preparing a series of four-, five- and six-membered cyclic silylselenides. Their fundamental properties were tailored by alternating the ring size, the number of embedded Se atoms and the used peripheral alkyl chains. In contrast to former preparations based on formation of sodium or lithium selenides, the newly developed synthetic method utilizes a direct and easy reaction of elemental selenium with chlorosilanes. Novel 2,2,4,4-tetraisopropyl-1,3,2,4-diselenadisiletane, which features good trade-off between chemical/thermal stability and reactivity, has been successfully used for gas-to-solid phase reaction with MoCl5affording MoSe2. A thorough characterization of the as-deposited 2D MoSe2flakes revealed its out-of-plane orientation and high purity. Hence, the developed four-membered cyclic silylselenide turned out to be well-suited Se-precursor for ALD of MoSe2
- Bure?, Filip,Charvot, Jaroslav,Jelínková, Veronika,Klikar, Milan,Krumpolec, Richard,Macak, Jan M.,Pavliňák, David,Pokorny, Daniel,Rodriguez-Pereira, Jhonatan,Zazpe, Raul
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- Direct thermal neutron detection by the 2D semiconductor 6LiInP2Se6
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Highly efficient neutron detectors are critical in many sectors, including national security1,2, medicine3, crystallography4 and astronomy5. The main neutron detection technologies currently used involve 3He-gas-filled proportional counters6 and light scintillators7 for thermalized neutrons. Semiconductors could provide the next generation of neutron detectors because their advantages could make them competitive with or superior to existing detectors. In particular, solids with a high concentration of high-neutron-capture nuclides (such as 6Li, 10B) could be used to develop smaller detectors with high intrinsic efficiencies. However, no promising materials have been reported so far for the construction of direct-conversion semiconductor detectors. Here we report on the semiconductor LiInP2Se6 and demonstrate its potential as a candidate material for the direct detection of thermal neutrons at room temperature. This compound has a good thermal-neutron-capture cross-section, a suitable bandgap (2.06 electronvolts) and a favourable electronic band structure for efficient electron charge transport. We used α particles from an 241Am source as a proxy for the neutron-capture reaction and determined that the compact two-dimensional (2D) LiInP2Se6 detectors resolved the full-energy peak with an energy resolution of 13.9 per cent. Direct neutron detection from a moderated Pu–Be source was achieved using 6Li-enriched (95 per cent) LiInP2Se6 detectors with full-peak resolution. We anticipate that these results will spark interest in this field and enable the replacement of 3He counters by semiconductor-based neutron detectors.
- Chica, Daniel G.,He, Yihui,McCall, Kyle M.,Chung, Duck Young,Pak, Rahmi O.,Trimarchi, Giancarlo,Liu, Zhifu,De Lurgio, Patrick M.,Wessels, Bruce W.,Kanatzidis, Mercouri G.
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- Soluble semiconductors AAsSe2 (A = Li, Na) with a direct-band-gap and strong second harmonic generation: A Combined experimental and theoretical study
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AAsSe2 (A = Li, Na) have been identified as a new class of polar direct-band gap semiconductors. These I - V - Vl2 ternary alkali-metal chalcoarsenates have infinite single chains of (1/∞)[AsQ 2] derived from corner-sharing pyramidal AsQ3 units with stereochemically active lone pairs of electrons on arsenic. The conformations and packing of the chains depend on the structure-directing alkali metals. This results in at least four different structural types for the Li1 xNaxAsSe2 stoichoimetry (α-LiAsSe 2, β-LiAsSe2, γ-NaAsSe2, and δ-NaAsSe2). Single-crystal X-ray diffraction studies showed an average cubic NaCI-type structure for (α-LiAsSe2, which was further demonstrated to be locally distorted by pair distribution function (PDF) analysis. The β and γ forms have polar structures built of different (1/∞)[AsSe2] chain conformations, whereas the δ form has nonpolar packing. A wide range of direct band gaps are observed, depending on composition: namely, 1.11 eV for (α-LiAsSe2, 1.60 eV for LiAsS2, 1.75 eV for γ-NaAsSe2, 2.23 eV for NaAsS2. The AAsQ2 materials are soluble in common solvents such as methanol, which makes them promising candidates for solution processing. Band structure calculations performed with the highly precise screenedexchange sX-LDA FLAPW method confirm the direct-gap nature and agree well with experiment. The polar y-NaAsSe2 shows very large nonlinear optical (NLO) second harmonic generation (SHG) response in the wavelength range of 600-950 nm. The theoretical studies confirm the experimental results and show that y-NaAsSe2 has the highest static SHG coefficient known to date, 337.9 pm/V, among materials with band gaps larger than 1.0 eV.
- Bera, Tarun K.,Jang, Joon I.,Song, Jung-Hwan,Malliakas, Christos D.,Freeman, Arthur J.,Ketterson, John B.,Kanatzidis, Mercouh G.
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- Extended Chemical Flexibility of Cubic Anti-Perovskite Lithium Battery Cathode Materials
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Novel bichalcogenides with the general composition (Li2TM)ChO (TM = Mn, Co; Ch = S, Se) were synthesized by single-step solid-state reactions. These compounds possess cubic anti-perovskite crystal structure with Pm3m symmetry; TM and Li are disordered on the crystallographic site 3c. According to Goldschmidt tolerance factor calculations, the available space at the 3c site is too large for Li+ and TM2+ ions. As cathode materials, all title compounds perform less prominent in lithium-ion battery setups in comparison to the already known TM = Fe homologue; e.g., (Li2Co)SO has a charge density of about 70 mAh g-1 at a low charge rate. Nevertheless, the title compounds extend the chemical flexibility of the anti-perovskites, revealing their outstanding chemical optimization potential as lithium battery cathode material.
- Lai, Kwing To,Antonyshyn, Iryna,Prots, Yurii,Valldor, Martin
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- Synthesis, Structure and Application of Intramolecularly-Coordinated Gallium Chalcogenides: Suitable Single-Source precursors for GaxSey Materials
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Studies have been focused on the synthesis of N→Ga-coordinated organogallium selenides and tellurides [L1Ga(μ-Se)]2 (1), [L2Ga(μ-Se)]2 (2) and [L1Ga(μ-Te)]2 (3), respectively, containing either N,C,N- or C,N-chelating ligands L1, 2 (L1 is {2,6-(Me2NCH2)2C6H3}? and L2 is {2-(Et2NCH2)-4,6-tBu2-C6H2}?) having Ga/E (E=Se or Te) atoms in 1/1 ratio. To change the Ga/E ratio, an unusual N→Ga-coordinated organogallium tetraselenide L1Ga(κ2-Se4) (4) was prepared. An unprecedented complex (L1Ga)2(μ-Te2)(μ-Te) (5), as the result of the non-stability of 3, was also isolated. Compound 2 is a suitable single-source precursor for the preparation of amorphous GaSe thin films by the spin coating. Moreover, simple heating of an octadecylamine solution of 2 provided, after work up, monoclinic Ga2Se3 crystals with different crystallinity according to conditions used. Therefore, compound 2 may be also used as a source of Ga2Se3 in the low-temperature doping process of Bi2Se3.
- ?i?ica, Tomá?,Bene?, Ludvík,Bou?ka, Marek,Dostál, Libor,Jambor, Roman,Knotek, Petr,Macak, Jan M.,Němec, Petr,R??i?ková, Zdenka,Ruleová, Pavlína
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- Synthesis, crystal structure and lithium motion of Li8SeN 2 and Li8TeN2
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The compounds Li8EN2 with E = Se, Te were obtained in form of orange microcrystalline powders from reactions of Li2E with Li3N. Single crystal growth of Li8SeN2 additionally succeeded from excess lithium. The crystal structures were refined using single-crystal X-ray diffraction as well as X-ray and neutron powder diffraction data (I41md, No. 109, Z = 4, Se: a = 7.048(1) A, c = 9.995(1) A, Te: a = 7.217(1) A, c= 10.284(1) A). Both compounds crystallize as isotypes with an anionic substructure motif known from cubic Laves phases and lithium distributed over four crystallographic sites in the void space of the anionic framework. Neutron powder diffraction pattern recorded in the temperature range from 3 K to 300 K and X-ray diffraction patterns using synchrotron radiation taken from 300 K to 1000 K reveal the structural stability of both compounds in the studied temperature range until decomposition. Motional processes of lithium atoms in the title compounds were revealed by temperature dependent NMR spectroscopic investigations. Those are indicated by significant changes of the 7Li NMR signals. Lithium motion starts for Li8SeN2 above 150 K whereas it is already present in Li8TeN2 at this temperature. Quantum mechanical calculations of NMR spectroscopic parameters reveal clearly different environments of the lithium atoms determined by the electric field gradient, which are sensitive to the anisotropy of charge distribution at the nuclear sites. With respect to an increasing coordination number according to 2 + 1, 3, 3 + 1, and 4 for Li(3), Li(4), Li(2), and Li(1), respectively, the values of the electric field gradients decrease. Different environments of lithium predicted by quantum mechanical calculations are confirmed by 7Li NMR frequency sweep experiments at low temperatures.
- Braeunling, Daniel,Pecher, Oliver,Trots, Dmytro M.,Senyshyn, Anatoliy,Zherebtsov, Dmitry A.,Haarmann, Frank,Niewa, Rainer
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- LiGaGe2Se6: A new IR nonlinear optical material with low melting point
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The new compound LiGaGe2Se6 has been synthesized. It crystallizes in the orthorhombic space group Fdd2 with a = 12.501(3) A, b = 23.683(5) A, c = 7.1196(14) A, and Z = 8. The structure is a three-dimensional framework composed of corner-sharing LiSe4, GaSe4, and GeSe4 tetrahedra. The compound exhibits a powder second harmonic generation signal at 2 μm that is about half that of the benchmark material AgGaSe2 and possesses a wide band gap of about 2.64(2) eV. LiGaGe2Se6 melts congruently at a rather low temperature of 710 °C, which indicates that bulk crystals can be obtained by the Bridgman-Stockbarger technique. According to a first-principles calculation, there is strong hybridization of the 4s and 4p orbitals of Ga, Ge, and Se around the Fermi level. The calculated birefractive index is Δn = 0.04 for λ ≥ 1 μm, and the calculated major SHG tensor elements are d15 = 18.6 pm/V and d33 = 12.8 pm/V. This new material is promising for application in IR nonlinear optics.
- Mei, Dajiang,Yin, Wenlong,Feng, Kai,Lin, Zheshuai,Bai, Lei,Yao, Jiyong,Wu, Yicheng
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- Oxidative Addition to SnII Guanidinate Complexes: Precursors to Tin(II) Chalcogenide Nanocrystals
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SnS, SnSe and SnTe are potentially important semiconductor materials. Here, we describe the application of chalcogen containing SnIV guanidinate precursors for the production of tin(II) chalcogenide nanocrystals. Reaction of the stannylene(II)
- Ahmet, Ibrahim Y.,Thompson, Joseph R.,Johnson, Andrew L.
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- Li6+2x[B10Se18]Sex (x ≈ 2), an ion-conducting double salt
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Li6+2x[B10Se18]Sex (x ≈ 2) was prepared in a solid state reaction from lithium selenide, amorphous boron and selenium in evacuated carbon coated silica tubes at a temperature of 800 °C. Subsequent cooling from 600 °C to 300 °C gave amber colored crystals with the following lattice parameters: space group I2/a (at 173K); a = 17.411(1) A, b = 21.900(1) A, c = 17.820(1) A, β = 101.6(1)°. The crystal structure contains a well-defined polymeric selenoborate network of composition ([B10Se16Se 4/2]6-)n consisting of a system of edge-sharing [B10Se16Se4/2] adamantanoid macrotetrahedra forming large channels in which a strongly disorderd system of partial occupied Li+ cations and additional disordered Se2- anions is observed. The crystal structure of the novel selenoborate is isotypic to Li 6+2x[B10S18]Sx (x = 2) [1]. X-ray and 7Li magic-angle spinning NMR data suggest that the site occupancies of the three crystallographically distinct lithium ions exhibit a significant temperature dependence. The lithium ion mobility has been characterized by detailed temperature dependent NMR lineshape and spin-lattice relaxation measurements.
- Hammerschmidt,Doech,Puetz,Eckert,Krebs
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- Syntheses and characterization of some mixed Te/Se polychalcogenide anions [TemSen]2-
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Several mixed Te/Se polychalcogenide anions [TemSe n]2- were synthesized at 293 K by reactions between Ten2- and Sen2- anions in N,N-dimethylformamide (DMF) in the presence of different-size ammonium or phosphonium cations, in some cases in the presence of metal species. The structures of these anions were determined by single-crystal X-ray diffraction methods. The crystal structures of (NEt4]2[Te 3Se6] (1) and [NEt4]2[Te 3Se7] (2) consist, respectively, of one-dimensional infinite ∞1[Te3Se6 2-] and ∞1[Te3Se 72-] anionic chains separated by NEt4 + cations. In compound 1, each chain comprises Te3Se 5 eight-membered rings bridged by Se atoms. The Te3Se 5 ring has an open book conformation. The NMR spectrum of a DMF solution of [NEt4]2[Te3Se6] crystals at 223 K shows 77Se resonances at δ = 290, 349, and 771 ppm and a single 125Te resonance at δ = 944.7 ppm. In compound 2, each chain comprises Te3Se6 five- and six-membered rings bridged by Se atoms. The Te3Se6 ring can be regarded as an inorganic analogue of bicyclononane. The anion of [PPh4]2[Te2Se2] (4) contains a Se-Te-Te-Se chain with the terminal Se atoms trans to one another. The new compounds [PPN]2[TeSe10] (3), [NMe4] 2[TeSe3]·DMF (5), and [NEt4] 2[TeSe3] (6) contain known anions.
- Sekar, Perumal,Ibers, James A.
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- (De)lithiation mechanism of Li/SeSx (x = 0-7) batteries determined by in situ synchrotron x-ray diffraction and X-ray absorption spectroscopy
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Electrical energy storage for transportation has gone beyond the limit of converntional lithium ion batteries currently. New material or new battery system development is an alternative approach to achieve the goal of new high-energy storage system with energy densities 5 times or more greater. A series of SeSx-carbon (x = 0-7) composite materials has been prepared and evaluated as the positive electrodes in secondary lithium cells with ether-based electrolyte. In situ synchrotron high-energy X-ray diffraction was utilized to investigate the crystalline phase transition during cell cycling. Complementary, in situ Se K-edge X-ray absorption near edge structure analysis was used to track the evolution of the Se valence state for both crystalline and noncrystalline phases, including amorphous and electrolyte-dissolved phases in the (de)lithiation process. On the basis of these results, a mechanism for the (de)lithiation process is proposed, where Se is reduced to the polyselenides, Li2Sen (n ≥ 4), Li2Se2, and Li2Se sequentially during the lithiation and Li2Se is oxidized to Se through Li2Sen (n ≥ 4) during the delithiation. In addition, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy demonstrated the reversibility of the Li/Se system in ether-based electrolyte and the presence of side products in the carbonate-based electrolytes. For Li/SeS2 and Li/SeS7 cells, Li 2Se and Li2S are the discharged products with the presence of Se only as the crystalline phase in the end of charge.
- Cui, Yanjie,Abouimrane, Ali,Lu, Jun,Bolin, Trudy,Ren, Yang,Weng, Wei,Sun, Chengjun,Maroni, Victor A.,Heald, Steve M.,Amine, Khalil
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- Structure Tuning, Strong Second Harmonic Generation Response, and High Optical Stability of the Polar Semiconductors Na1- xKxAs Q2
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The mixed cation compounds Na1-xKxAsSe2 (x = 0.8, 0.65, 0.5) and Na0.1K0.9AsS2 crystallize in the polar noncentrosymmetric space group Cc. The AAsQ2 (A = alkali metals, Q = S, Se) family features one-dimensional (1D) 1/∞[AQ2-] chains comprising corner-sharing pyramidal AQ3 units in which the packing of these chains is dependent on the alkali metals. The parallel 1/∞[AQ2-] chains interact via short As···Se contacts, which increase in length when the fraction of K atoms is increased. The increase in the As···Se interchain distance increases the band gap from 1.75 eV in γ-NaAsSe2 to 2.01 eV in Na0.35K0.65AsSe2, 2.07 eV in Na0.2K0.8AsSe2, and 2.18 eV in Na0.1K0.9AsS2. The Na1-xKxAsSe2 (x = 0.8, 0.65) compounds melt congruently at approximately 316 °C. Wavelength-dependent second harmonic generation (SHG) measurements on powder samples of Na1-xKxAsSe2 (x = 0.8, 0.65, 0.5) and Na0.1K0.9AsS2 suggest that Na0.2K0.8AsSe2 and Na0.1K0.9AsS2 have the highest SHG response and exhibit significantly higher laser-induced damage thresholds (LIDTs). Theoretical SHG calculations on Na0.5K0.5AsSe2 confirm its SHG response with the highest value of d33 = 22.5 pm/V (χ333(2) = 45.0 pm/V). The effective nonlinearity for a randomly oriented powder is calculated to be deff = 18.9 pm/V (χeff(2) = 37.8 pm/V), which is consistent with the experimentally obtained value of deff = 16.5 pm/V (χeff(2) = 33.0 pm/V). Three-photon absorption is the dominant mechanism for the optical breakdown of the compounds under intense excitation at 1580 nm, with Na0.2K0.8AsSe2 exhibiting the highest stability.
- Iyer, Abishek K.,Cho, Jeong Bin,Byun, Hye Ryung,Waters, Michael J.,Hao, Shiqiang,Oxley, Benjamin M.,Gopalan, Venkat,Wolverton, Christopher,Rondinelli, James M.,Jang, Joon I.,Kanatzidis, Mercouri G.
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p. 18204 - 18215
(2021/11/12)
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- Traceless selenocarboxylates for the one-pot synthesis of amides and derivatives
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We have recently reported a one-pot procedure for glycosyl amides synthesis using selenocarboxylate as traceless reagent. Herein, we present a further application of selenocarboxylate-azide reaction for amide bond formation on a broader range of substrates, including heterocyclic systems and fatty acid. This method proved to be highly efficient for the synthesis of primary and secondary amides, sulfonamides, imides, phosphoramide and also carbamate.
- Silva, Luana,Rosário, Alisson R.,Machado, Bianca M.,Lüdtke, Diogo S.
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supporting information
(2020/12/25)
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- From elusive thio- and selenosilanoic acids to copper(i) complexes with intermolecular Si=E → Cu-O-Si coordination modes (E = S, Se)
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The facile synthesis of the first stable selenosilanoic acid-base adduct LSi(=Se)OH(dmap) 3 (L = CH[C(Me)NAr]2, Ar = 2,6-iPr2C 6H3, dmap = 4-dimethylaminopyridine), the heavier analogue of the thiosilanoic acid adduct LSi(=S)OH(dmap) 1, is reported. Both adducts 1 and 3 react readily with MesCu (Mes = 2,4,6-trimethylphenyl) to form the novel dimeric Cu(i) complexes [LSi(=E)OCu]2 (4: E = S; 5: E = Se) with unprecedented intermolecular Si=E → Cu-O-Si coordination modes. The latter are efficient pre-catalysts for the Cu(i)-mediated aziridination of styrene with Ph=IN(Ts) (Ts = tosyl).
- Tan, Gengwen,Xiong, Yun,Inoue, Shigeyoshi,Enthaler, Stephan,Blom, Burgert,Epping, Jan D.,Driess, Matthias
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p. 5595 - 5597
(2013/07/26)
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- Ba2AgInS4 and Ba4MGa5Se 12 (M = Ag, Li): Syntheses, structures, and optical properties
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The first two members in alkaline-earth/group XI/group XIII/chalcogen system, namely Ba2AgInS4 and Ba4AgGa 5Se12, were synthesized along with a Li analogue Ba 4LiGa5Se12. Ba2AgInS4 crystallizes in space group P21/c. It contains 2∞[AgInS 4]4- layers built from AgS3 triangles and InS4 tetrahedra with Ba2+ cations inserted between the layers. Ba4AgGa5Se12 and Ba 4LiGa5Se12 adopt two closely-related structure types in space group P421c with structural difference originating from the different positions of Ag and Li in them. The three-dimensional framework in Ba4AgGa5Se12 is composed of GaSe4 tetrahedra with the Ba and Ag atoms occupying the large and small channels respectively, whereas that in Ba4LiGa 5Se12 is built from LiSe4 and GaSe4 tetrahedra with channels to accommodate the Ba atoms. As deduced from the diffuse reflectance spectra measurement, the optical band gaps were 2.32 (2) eV, 2.52 (2) eV, and 2.65 (2) eV for Ba2AgInS4, Ba 4AgGa5Se12, and Ba4LiGa 5Se12, respectively. The Royal Society of Chemistry 2012.
- Yin, Wenlong,Feng, Kai,Mei, Dajiang,Yao, Jiyong,Fu, Peizhen,Wu, Yicheng
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p. 2272 - 2276
(2012/03/22)
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- Synthesis, structure, and properties of Li2In2MQ 6 (M = Si, Ge; Q = S, Se): A new series of IR nonlinear optical materials
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The four isostructural compounds Li2In2MQ6 (M = Si, Ge; Q = S, Se) have been synthesized for the first time. They crystallize in the noncentrosymmetric monoclinic space group Cc with the three-dimensional framework composed of corner-sharing LiQ4, InQ 4, and MQ4 tetrahedra. The second-harmonic-generation signal intensities of the two sulfides and two selenides were close to those of AgGaS2 and AgGaSe2, respectively, when probed with a laser with 2090 nm as the fundamental wavelength. They possess large band gaps of 3.61(2) eV for Li2In2SiS6, 3.45(2) eV for Li2In2GeS6, 2.54(2) eV for Li 2In2SiSe6, and 2.30(2) eV for Li 2In2GeSe6, respectively. Moreover, these four compounds all melt congruently at relatively low temperatures, which makes it feasible to grow bulk crystals needed for practical application by the Bridgman-Stockbarger method.
- Yin, Wenlong,Feng, Kai,Hao, Wenyu,Yao, Jiyong,Wu, Yicheng
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p. 5839 - 5843
(2012/06/30)
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- Synthesis and structures of polychalcogenadistannabicyclo[k.l.m]alkanes
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Reaction of steric encumbered trichlorostannane with disodium sulfide or dilithium selenide gave 2,4-dimercapto-1,3,2,4-dithiadistannetane or tetraselenadistannabicyclo[2.1.1]hexane, respectively. Reactions of steric encumbered trihydrostannane with elemental chalcogens gave pentachalcogenadistannabicyclo[k.1.1]heptanes (k = 2 and 3). The two bridgehead tin atoms of the first polychalcogenadistannabicyclo[k.l.m]alkanes are concluded to have no significant bonding interaction, judging from the longer bond distances than those of the normal tin-tin single bonds.
- Saito, Masaichi,Hashimoto, Hizuru,Tajima, Tomoyuki,Ikeda, Masatoshi
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p. 2729 - 2735
(2008/02/03)
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- Molecular structures of trimeric diphenyltin chalcogenides, (Ph2SnE)3, E = S, Se, Te
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The trimeric diphenyltin chalcogenides (Ph2SnE)3 (E=S (1), Se (2), Te(3)) have been synthesized by reaction of Ph2SnCl2 with Li2E and characterized by multinuclear NMR spectroscopy (1H, 13C, 119Sn, 77Se and 125Te) as well as crystal structure analyses. The three compounds crystallize in the monoclinic space group P21/n and show central six-membered rings Sn3E3 in twisted boat conformations. For 1 density functional theory (DFT) calculations at the B3LYP/6-31G* level of theory have revealed the twisted boat conformation as the global minimum. Additionally a boat conformation (+3.4 kJ mol-1) and a chair conformation (+7.9 kJ mol-1) have been calculated. The mutual repulsion of the phenyl rings in the chair conformation is also evident from the increased bond angles of the Sn3S3 ring in 1.
- Lange, Heike,Herzog, Uwe,B?hme, Uwe,Rheinwald, Gerd
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- Five- and six-membered ring Group 14 chalcogenides of the types (Me2ME)3 (M=Si, Ge, Sn), E(Si2Me4)2E, Me4Si2(E)2MRx (MRx=C(CH2)5, SiMe2, GeMe2, SnMe2, SnPh2, BPh)
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The reactions of Me2MCl2 (M=Si, Ge, Sn) with either H2S/NEt3 or Li2E (E=Se, Te) yielded the six-membered-ring compounds (Me2ME)3. Similarly the treatment of ClMe2SiSiMe2Cl (1) with H2S/NEt3 or Li2E resulted in the formation of E(Si2Me4)2E. Mixed species E(Si2Me4)2E′ could be obtained by reaction with mixtures of Li2E and Li2E′ or in the presence of traces of moisture (E′=O). Reactions of 1:1 mixtures of Me2MCl2 and 1 with Li2E resulted in exclusive or at least preferred formation of five-membered rings Me4Si2(E)2MMe2. A carbon analogue, Me4Si2(S)2C(CH2)5, was obtained from 1 and (HS)2C(CH2)5. Boron could also be introduced in these ring systems, starting from PhBCl2 and 1 the compounds PhB(E)2Si2Me4 (E=S, Se) could be synthesized. Mixtures of 1 and Cl2MeSiSiMeCl2 yielded, on treatment either with H2S/NEt3 or Li2E (E=Se, Te), the bis(cyclopentyl) compounds [Me4Si2(E)2SiMe-]2. All products have been characterized by multinuclear NMR (1H, 11B, 13C, 29Si, 77Se, 119Sn, 125Te) measurements including coupling constants. Trends of chemical shifts and coupling constants are discussed. The crystal structures of E(Si2Me4)2E (E=S, Se) and [Me4Si2(S)2SiMe-]2 are reported.
- Herzog,Rheinwald
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- New soluble monomeric polyselenide anions, [MQ(Se4)2]2- (M = Mo, W; Q = O, S, Se)
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Reaction of MO42- (M = Mo, W) with [(CH3)2(CH3(CH2) 7)Si]2Se provides a new synthetic route to the tetraselenometalates MSe42-. Reaction of MSe42- with Se8, SeS2, or Se4(NC5H10)2 affords the MQ(Se4)22- ion with Q = Se, S, or O, respectively. 77Se NMR studies of this system confirm the general assignment trends of terminal Se (>1200 ppm), metal bound Se (1200-600 ppm), and ring Se (17O and previous 77Se NMR studies. The compound [NEt4]2[MoO(Se4)2] crystallizes in the monoclinic space group P21/c with a = 9.287 (2) ?, b = 17.132 (4) ?, c = 18.353 (4) ?, β = 97.38 (1)°, and Z = 4. The MoO(Se4)22- ion shows square-pyramidal coordination of the MoIV center by the apical O atom and the two bidentate Se42- units. [PPh4]2[WS(Se4)2] crystallizes in the monoclinic space group P21/a with a = 18.366 (7) ?, b = 12.873 (6) ?, c = 20.666 (8) ?, β = 100.74 (1)°, and Z = 4. WS(Se4)22- is structurally analogous to MoO(Se4)22-. All of the MSe4 (M = Mo, W) rings exhibit conformations similar to that of cyclopentane.
- Wardle, Robert W. M.,Mahler, Charles H.,Chau, Chung-Nin,Ibers, James A.
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p. 2790 - 2795
(2008/10/08)
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