Transition metal carbides. A comparison of bonding in extended and molecular interstitial carbides

Wijeyesekera, Sunil D.; Hoffmann, Roald

doi:10.1021/om00085a001

Cited by 123 publications

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“…Thus, the sign is inverted with respect to the crystal orbital overlap population (COOP) diagrams originally used in semi-empirical extended-Hückel calculations. [30] For TlF [31] in space group Pbnm, TlCl [32] and TlBr [32] in the CsCl (Pm3m) and NaCl (Fm3m) structures as well as for TlI in the CsCl [8] structure and its low-temperature modification, [33] the structural data were employed as reported in the literature. Lattice constants for a hypothetical TlF in the rock-salt structure were estimated from the molar volume of room temperature TlF in space group Pbcm.…”

Section: Computational Detailsmentioning

confidence: 99%

Thallium Halides – New Aspects of the Stereochemical Activity of Electron Lone Pairs of Heavier Main‐Group Elements

Mudring

2007

Eur J Inorg Chem

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Keywords: Halides / Thallium / Electron lone pairsDensity functional theory studies in the linear muffin tin approximation on thallium halides (TlX; X = F, Cl, Br, I) show that structural distortions due to a stereochemically active lone pair of electrons depend crucially on cation-anion interactions. Such distortions do not originate from a 6s-6p hybridisation on the heavy metal as the Tl 6s and 6p states are energetically too far apart to mix directly. In the case of TlF, the Tl 6s and the F 2p states are located in the same energy region, which leads to an efficient interaction that produces strongly antibonding Tl-F states directly below the Fermi level that would destabilize the solid. Minimisation of these

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Section: Computational Detailsmentioning

confidence: 99%

Thallium Halides – New Aspects of the Stereochemical Activity of Electron Lone Pairs of Heavier Main‐Group Elements

Mudring

2007

Eur J Inorg Chem

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“…The ground state degeneracy is caused by antiferromagnetic coupling between the triangular arrangement of columns, that is, geometric frustration. [21] …”

Section: Resultsmentioning

confidence: 99%

{Os₅Lu₂₀}I₂₄, the First Extended Cluster Complex of Lutetium with Eight‐Coordinate Endohedral Osmium Atoms in Two Different Environments

et al. 2011

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Keywords:Cluster compounds / Synthetic methods / Rare earths / Lutetium / Osmium / Electronic structure / Magnetic properties / Endohedral atoms {Os 5 Lu 20 }I 24 was obtained from a conproportionation reaction of lutetium and lutetium triiodide in the presence of osmium in an arc-welded tantalum container at 850-1200°C. The crystal structure has been determined by single-crystal X-ray diffraction analysis. Square antiprisms and cubes of lutetium atoms in a 4:1 ratio share common square faces in a chain; they encapsulate osmium atoms and are surrounded by iodide ions. Os-Os distances within the cluster chains (299, 303, and 325 pm) imply only little if no bonding between neighbouring osmium atoms. The cluster complex chains are packed in the fashion of a hexagonal closest packing of rods.

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“…The crystalline structure of the γ-Nb 2 C belongs to the P6 3 /mmc space group (space group number 194) with the prototype structure of the W 2 C phase [17]. Its stacking sequence can be described as AbAb where A refers to the metallic atoms and b refers to the carbon atoms [2,26]. The ordered β-Nb 2 C belongs to the P31m space group (space group Number 162).…”

Section: The C-nb Phase Diagrammentioning

confidence: 99%

“…In one of these sub-lattices, the positions are occupied by metallic atoms and in the other by carbon atoms. The stacking sequence of this phase can be described as AbCaBc, where A, B or C refer to the metallic atoms and a, b or c to the carbon atoms [26]. The atoms in this structure have octahedral coordination, and the carbon atoms occupy half of the octahedral interstices of the metallic sub-lattice [3].…”

Section: The C-nb Phase Diagrammentioning

confidence: 99%

Physical Properties of the NbC Carbide

Cuppari

Santos

2016

Metals

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Transition metal carbides are interesting materials with a singular combination of properties, such as high melting points, high hardness, good transport properties and relatively low costs, which makes them excellent candidates for several technological applications. The possible applications of NbC carbide remained unexplored as it was in the past expensive and available in limited volumes. In order to guide investigations of the applicability of NbC, a deeper understanding of the physical properties of this carbide is fundamental. In this review paper, key physical properties of NbC are compiled with emphasis on its chemical bonding, a careful description of the C-Nb phase diagram, the phases formed and the crystal structures. Thermal properties are discussed and correlated with the intrinsic and extrinsic features of NbC. Finally, elastic properties are discussed.

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Transition metal carbides. A comparison of bonding in extended and molecular interstitial carbides

Cited by 123 publications

References 0 publications

Thallium Halides – New Aspects of the Stereochemical Activity of Electron Lone Pairs of Heavier Main‐Group Elements

Thallium Halides – New Aspects of the Stereochemical Activity of Electron Lone Pairs of Heavier Main‐Group Elements

{Os₅Lu₂₀}I₂₄, the First Extended Cluster Complex of Lutetium with Eight‐Coordinate Endohedral Osmium Atoms in Two Different Environments

Physical Properties of the NbC Carbide

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Transition metal carbides. A comparison of bonding in extended and molecular interstitial carbides

Cited by 123 publications

References 0 publications

Thallium Halides – New Aspects of the Stereochemical Activity of Electron Lone Pairs of Heavier Main‐Group Elements

Thallium Halides – New Aspects of the Stereochemical Activity of Electron Lone Pairs of Heavier Main‐Group Elements

{Os5Lu20}I24, the First Extended Cluster Complex of Lutetium with Eight‐Coordinate Endohedral Osmium Atoms in Two Different Environments

Physical Properties of the NbC Carbide

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{Os₅Lu₂₀}I₂₄, the First Extended Cluster Complex of Lutetium with Eight‐Coordinate Endohedral Osmium Atoms in Two Different Environments