The nature of the chemical bonding in boron carbide, B<sub>13</sub>C<sub>2</sub>. II. Dynamic deformation densities and valence densities

Kirfel, Α.; Gupta, A.; Will, G.

doi:10.1107/s056774087900916x

Cited by 27 publications

(11 citation statements)

References 10 publications

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“…On the other hand, ionicity depends on charge density distribution, i.e. chemical environment is important [29,43]. So, the polar to equatorial bonds (B8-B9 and B10-B11 bonds) in the icosahedra units have the largest ionicity (0.449) in the Ie-CBC and Ie-CCB configurations, in good agreement with other theoretical values [7].…”

Section: Ip-bccsupporting

confidence: 83%

“…Ie-CCB bond structures [43], and if the deformation density is perpendicular to the chain line, then a significant charge transfer is found within the CBC chain from B to C. This accumulation could be associated with the overlap of an sp orbital of B with an sp 3 orbital of C [43]. In addition to this chemical situation, the very large thermal factor for the central boron atom of the chain implies a loosely bound boron cation rather than a strong and stiff covalently bonded boron atom [19,29,45].…”

Section: Ip-ccbmentioning

confidence: 99%

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Hypothetically superhard boron carbide structures with a B₁₁C icosahedron and three‐atom chain

Aydın

Şi̇mşek

2008

Physica Status Solidi (b)

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The structural and mechanical properties are investigated for the phases of superhard boron carbide, B4C, by performing DFT/PW91 level calculations. In addition to B12 icosahedra and CCC chains, we suggest new types of hypothetically stable rhombohedral structures of boron carbide, configurations that consist of one icosahedron, B11C, and a three‐atom chain such as CBC, CCB and BCC. Our results indicate that all phases are promising superhard materials, the hardness of all of them being greater than 40 GPa. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Ip-bccsupporting

confidence: 83%

Section: Ip-ccbmentioning

confidence: 99%

Hypothetically superhard boron carbide structures with a B₁₁C icosahedron and three‐atom chain

Aydın

Şi̇mşek

2008

Physica Status Solidi (b)

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“…A significantly higher charge accumulation is observed in the inter-icosahedral bonding between icosahedra along the c-axis. On the icosahedra itself we observe as in other studies involving icosahedra [18] a rather even charge distribution with the charges ªsmearedº out more or less evenly over the icosahedral surface.…”

Section: New Refinementsupporting

confidence: 65%

Electron Deformation Density in Rhombohedral α-Boron

Will

Kiefer

2001

Z. anorg. allg. Chem.

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a-boron is the most simple structure of all boron modifications having one B 12 icosahedron per (rhombohedral) unit cell. The conventional, free atom crystal structure refinement with R = 6.2% indicates considerable charge redistribution into covalent bonding. In a high order-low order and multipole refinement the R value could be reduced to 1.19%. The ensuing deformation difference density maps reveal bonding between the boron atoms, in the icosahedra and between the icosahedra. Elektronen-Deformationsdichte in rhomboedrischem a-BorInhaltsu È bersicht. a-Bor ist die einfachste von den drei bekannten Bor Phasen, mit nur einer ikosaedrischen B 12 Einheit pro (rhomboedrischer) Elementarzelle. Eine konventionelle Strukturanalyse und Verfeinerung ergab einen R-Wert von nur 6.2%. Dies deutete auf eine erhebliche ElektronenUmverteilung in die Bor±Bor-Bindungen hin. Mit einer ¹high order-low orderª und Multipol Verfeinerung konnte der R-Wert auf 1.19% reduziert werden. Die berechneten Differenz-Deformations-Elektronendichten zeigten deutliche kovalente Bindungsanteile zwischen den Bor-Atomen, sowohl in den Ikosaedern als auch zwischen den Ikosaedern.

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“…[37] Examples of such maps for the tetrazole and thiophene fragments of LR-B/ 081 are shown in Figures 3 and 4, respectively. However, although appealing for their pictorial effectiveness and visual conciseness, such dynamic or static deformation maps may suffer from serious shortcomings, such as a dependence on data resolution (compare Figure 3a and 3b) or scale factors, [38] as well as on the radial parameters adopted in the multipole model. This hampers any quantitative comparison between results from different investigations if precise values for the positions of the D1(r) peaks and their heights are sought.…”

Section: Resultsmentioning

confidence: 99%

Progress in the Understanding of Drug–Receptor Interactions, Part 1: Experimental Charge‐Density Study of an Angiotensin II Receptor Antagonist (C₃₀H₃₀N₆O₃S) atT=17 K

Destro

Soave

Barzaghi

et al. 2005

Chemistry A European J

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An experimental study of the electron-density distribution rho(r) in an angiotensin II receptor antagonist 1 has been made on the basis of single-crystal X-ray diffraction data collected at a low temperature. The crystal structure of 1 consists of infinite ribbons in which molecules are connected by an N-H...N hydrogen bond and several interactions of the C-H...O, C-H...N, and C-H...S type. The molecular conformation, characterized by the syn orientation of a tetrazole and a pyrimidinone ring with respect to a phenyl spacer group, is stabilized by two short SO and SN intramolecular contacts between a substituted thiophene fragment and the other two heterocycles of 1. The electrostatic nature of these interactions is documented. Furthermore, the Laplacian of rho(r) in the plane defined by the sulfur, oxygen, and nitrogen atoms involved in these interactions shows their strongly directional character as the regions of charge concentration on the valence shell of the nitrogen and oxygen atoms directly face the regions of charge depletion on the valence shell of the sulfur atom. All the chemical bonds and the relevant intra- and intermolecular interactions of 1 have been quantitatively described by the topological analysis of rho(r). Simple relationships between the bond path lengths (R(b)) and the values of rho at the bond critical points (rho(bcp)) have been obtained for the 28 C-C bonds, the seven N-C bonds, and the four O-C bonds. For the first two classes of bonds the relationship is in the form of a straight line, whose parameters, for the C-C bonds, agree, within experimental uncertainty, with those previously derived in our laboratory from a 19 K X-ray diffraction study of crystals of a different compound. Maps of the molecular electrostatic potential phi(r) derived from the experimental charge density display features that are important for the drug-receptor recognition of 1.

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The nature of the chemical bonding in boron carbide, B₁₃C₂. II. Dynamic deformation densities and valence densities

Cited by 27 publications

References 10 publications

Hypothetically superhard boron carbide structures with a B₁₁C icosahedron and three‐atom chain

Hypothetically superhard boron carbide structures with a B₁₁C icosahedron and three‐atom chain

Electron Deformation Density in Rhombohedral α-Boron

Progress in the Understanding of Drug–Receptor Interactions, Part 1: Experimental Charge‐Density Study of an Angiotensin II Receptor Antagonist (C₃₀H₃₀N₆O₃S) atT=17 K

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The nature of the chemical bonding in boron carbide, B13C2. II. Dynamic deformation densities and valence densities

Cited by 27 publications

References 10 publications

Hypothetically superhard boron carbide structures with a B11C icosahedron and three‐atom chain

Hypothetically superhard boron carbide structures with a B11C icosahedron and three‐atom chain

Electron Deformation Density in Rhombohedral α-Boron

Progress in the Understanding of Drug–Receptor Interactions, Part 1: Experimental Charge‐Density Study of an Angiotensin II Receptor Antagonist (C30H30N6O3S) atT=17 K

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The nature of the chemical bonding in boron carbide, B₁₃C₂. II. Dynamic deformation densities and valence densities

Hypothetically superhard boron carbide structures with a B₁₁C icosahedron and three‐atom chain

Hypothetically superhard boron carbide structures with a B₁₁C icosahedron and three‐atom chain

Progress in the Understanding of Drug–Receptor Interactions, Part 1: Experimental Charge‐Density Study of an Angiotensin II Receptor Antagonist (C₃₀H₃₀N₆O₃S) atT=17 K