| 1. |
- Verchenko, V. Yu, et al.
(författare)
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Intermetallic solid solution Fe1-xCoxGa3 : Synthesis, structure, NQR study and electronic band structure calculations
- 2012
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 194, s. 361-368
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Tidskriftsartikel (refereegranskat)abstract
- Unlimited solid solution Fe1-xCoxGa3 was prepared from Ga flux. Its crystal structure was refined for Fe0.5Co0.5Ga3 (P4(2)/mnm, a=6.2436(9), c=6.4654(13), Z=4) and showed no ordering of the metal atoms. A combination of the electronic band structure calculations within the density functional theory (DFT) approach and Ga-69,Ga-71 nuclear quadrupole resonance (NRQ) spectroscopy clearly shows that the Fe-Fe and Co-Co dumbbells are preferred to the Fe-Co dumbbells in the crystals structure. The band structure features a band gap of about 0.4 eV, with the Fermi level crossing peaks of a substantial density of electronic states above the gap for x > 0. The solid solution is metallic for x > 0.025. The study of the nuclear spin-lattice relaxation shows that the rate of the relaxation, 1/T-1, is very sensitive to the Co concentration and correlates well with the square of the density of states at the Fermi level, N-2(E-F).
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| 2. |
- Baranov, A. I., et al.
(författare)
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Unique (infinity Ni8Bi8S)-Ni-1 metallic wires in a novel quasi-1D compound. Synthesis, crystal and electronic structure, and properties of Ni8Bi8SI
- 2001
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 123:49, s. 12375-12379
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Tidskriftsartikel (refereegranskat)abstract
- A new quasi-one-dimensional compound Ni8Bi8SI has been synthesized and its crystal structure determined from single-crystal X-ray diffraction data. The structure of Ni8Bi8SI consists of [(infinityNi8Bi8S)-Ni-1] columns separated by iodine atoms. Conductivity and magnetic susceptibility measurements (down to 4.2 K) show that Ni8Bi8SI is a one-dimensional metal and exhibits Pauli paramagnetic properties. These observations are in good agreement with the results from electronic structure calculations. An analysis of the chemical bonding employing difference electron charge density maps reveals strong multicenter Ni-Bi bonds and pair Ni-S interactions within the [(infinityNi8Bi8S)-Ni-1] columns. Only electrostatic interactions are inferred between the columns and iodine atoms.
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| 3. |
- Seisenbaeva, G. A., et al.
(författare)
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Homo- and hetero-metallic rhenium oxomethoxide complexes with a M-4(mu-O)(2)(mu-OMe)(4) planar core - a new family of metal alkoxides displaying a peculiar structural disorder. Preparation and X-ray single crystal study
- 2001
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Ingår i: Journal of the Chemical Society. Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1472-7773 .- 1364-5447. ; :19, s. 2762-2768
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Tidskriftsartikel (refereegranskat)abstract
- The reaction of Re2O7 with MeOH at room temperature leads to a fine black powder. A product with the same crystal structure, according to X-ray powder data, was obtained in the form of single crystals on storage of solutions of Re2O3(OMe)(6), obtained by anodic oxidation of Re metal. It was identified as Re4O6(OMe)(12) (1) by an X-ray single crystal study. A mixed-valence complex of analogous composition and structure, Re4O6-y (OMe)(12+y) (2), earlier erroneously described as Re4O2(OMe)(16), can be obtained via anodic dissolution of Re in MeOH using high current densities. The heterometallic members of this family, Re4-xMxO6-y(OMe)(12+y) [M = Mo (3), W (4); x less than or equal to 0.55, y < 1.0], were obtained by interaction of Re2O7 with MO(OMe)(4) or M(OMe)(6) in toluene at reflux. Mo-poor samples of 3 (x 0.25) could also be obtained on storage of solutions prepared by anodic oxidation of Re, in the presence of MoO(OMe)(4). The reaction of Re2O7 with Nb(OMe)(5) or Ta(OMe)(5) in refluxing toluene gave M-4(mu -O)(2)(mu -OMe)(4)(OMe)(14)(ReO4)(2) [M = Nb (5), Ta (6)] as the only crystalline products. The compounds 1-6 are insoluble in organic solvents and display a remarkable resistance to ambient atmosphere, making them attractive precursors for soft chemical preparation of rhenium metal and alloy powders.
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| 4. |
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| 5. |
- Lindsjö, Martin, et al.
(författare)
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Novel Compounds Sn14In10P22I8 and Sn14In10P21.2I8 with Clathrate-I Structure: Synthesis and Crystal and Electronic Structure
- 2001
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 161:2, s. 232-242
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Tidskriftsartikel (refereegranskat)abstract
- Two new supramolecular pnictidehalides Sn10In14P22I8 (I) anti Sn14In10P21.2I8 (II) have been synthesized using a standard ampoule technique. Both compounds possess the clathrate I type of structure. I crystallizes in the cubic space group Pm (3) over barn (No. 223) with the unit cell parameter a = 11.0450(7) (Z = 1) while II reveals a complicated superstructure (space group P4(2)/m (No. 84), a = 24.745(3) Angstrom, c = 11.067(1) Angstrom, Z = 5) resulting from the partial ordering of vacancies at phosphorus sites. The crystal structures have been solved based on single-crystal X-ray diffraction data sets (omega -2 theta) scans, least-squares refinement against F-2) to R = 0.0376 (Sn10In14P22I8) and R = 0.0569 (Sn14In10P21.2I8). In both structures metal anti phosphorus atoms form a cationic clathrate I framework hosting iodine atoms in the cavities. The composition of both phases complies with the Zintl-Klemm formalism which justifies the existence of vacancies in the structure of II. The Sn-119 Mossbauer spectroscopy data together with the results of the band structure calculations suggest that the electron density on tin atoms is reduced in favor of bands, which lie just below the Fermi level and must define electronic properties of the compounds in question. The differences in the crystal and electronic structures of the cationic tin clathrates are discussed.
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| 6. |
- Nikonova, Olesya A, et al.
(författare)
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Electrochemical Synthesis, Structural Characterization, and decomposition of Rhenium Oxoethoxide, Re4O4(OEt)12. Ligand Influence on the Structure and Bonding in the High-Valent Tetranuclear Planar Rhenium Alkoxide Clusters
- 2008
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Ingår i: Inorganic Chemistry. ; 47, s. 1295-1300
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Tidskriftsartikel (refereegranskat)abstract
- Anodic oxidation of rhenium in ethanol in the presence of LiCl as a conductive additive results with high yield information of a new oxoethoxide cluster, Re4O4(OEt)12. The structure of the planar centrosymmetric metal–oxygencore of this molecule is composed of four edge-sharing Re(V)O6 octahedra. Eight electrons are available for theformation of metal-metal bonds indicated by five relatively short Re-Re distances within the Re4-rhombus, a“planar butterfly” type cluster. The theoretical calculations are indicating relatively low contribution of metal-metalbonding in the stability of the core. The stability of the +V-oxidation state, unusual for rhenium alkoxides can beat least partially attributed to the size effects in the packing of ligands. The X-ray powder study indicates thattreatment of Re4O4(OEt)12 in ambient atmosphere rapidly transforms it into a mixed-valence derivativeRe4O6(OEt)10swith a structure related to the earlier investigated cluster Re4O6(OiPr)10. Thermal decomposition ofthe latter rhenium oxoethoxide results in reduction to rhenium metal at as low temperatures as 380 °C, producingaggregates of metal nanoparticles with the average size of 3 nm.
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