Experimental charge density study of (DBr-DCNQI)2Cu for metallic phase by synchrotron X-ray diffraction

2010 ◽  
Vol 405 (11) ◽  
pp. S321-S323
Author(s):  
S. Maki ◽  
E. Nishibori ◽  
H. Okabayashi ◽  
R. Sato ◽  
S. Aoyagi ◽  
...  
Keyword(s):  
Charge Density ◽  
Metallic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Study ◽  
Experimental Charge Density

Experimental charge density study on FLPs and a FLP reaction product

2018 ◽  
Vol 233 (9-10) ◽  
pp. 723-731
Author(s):  
Christian Joseph Schürmann ◽  
Regine Herbst-Irmer ◽  
Thorsten Lennart Teuteberg ◽  
Daniel Kratzert ◽  
Gerhard Erker ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Density ◽  
Theoretical Calculations ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
X Ray ◽  
Charge Densities ◽  
A Charge ◽  
Density Study ◽  
Experimental Charge Density

Abstract The charge density distribution of the intramolecular frustrated Lewis pair (FLP) Mes2PCH2CH2B(C6F5)2 (1), the phosphinimine HNPMes2CH2CH2B(C6F5)2 (2), as well as a FLP homologue with nitrogen NEt2CHPhCH2B(C6F5)2 (3) were investigated with Bader’s quantum theory of atoms in molecules (QTAIM). The charge densities were derived from both experimental high-resolution X-ray diffraction data (2, 3) and theoretical calculations (1, 3). The QTAIM analysis for the FLPs 1 and 3 showed the prominent B-pnictogen interaction to be weak dative bonds without significant charge-transfer. This holds also true for the B–N–bond of 2. The nitrogen atom is negatively charged, due to a charge transfer from phosphorous and shows features of a sp2-hybridization. The bond is therefore best described as a non-hypervalent Pδ+–Nδ− moiety.

Charge density study of the first mixed-valent tetraphosphete

2014 ◽  
Vol 70 (a1) ◽  
pp. C1345-C1345
Author(s):  
Verena Breuers ◽  
Christian Lehmann ◽  
Walter Frank
Keyword(s):  
Charge Density ◽  
Theoretical Calculations ◽  
X Ray Diffraction ◽  
Ring Plane ◽  
X Ray ◽  
Coordination Behavior ◽  
Rhombic Distortion ◽  
Electrostatic Contribution ◽  
Density Study ◽  
Experimental Charge Density

The first λ3,λ5-tetraphosphete contains a 4π-electron four-membered ring as the central structural unit of a dispirocyclic system and can thus be classified as an analogue to diphosphetes and cyclodiphosphazenes. According to its crystal structure the central P4unit exhibits not only P–P bonds which are of equal length (P1–P2 2,139(1) Å, P1–P2A 2,142(1) Å), but also rhombic distortion (P1–P2–P1A 79,4(1)0, P2–P1–P2A 100,6(1)0).[1] Therefore its electronic structure cannot be described as 'Phosphacyclobutadiene' but either as a bis(ylide) or as a system with delocalized double bonds. After various quantum chemical calculations and an extensive examination of its reaction and coordination behavior failed to answer this question, we addressed the problem via a detailed analysis of its charge density distribution. The experimental charge density based on high resolution X-ray diffraction data collected at low temperature is determined by multipole least squares refinement using the program packageXD2006.[2] In a first step, the static deformation density exhibits charge density which is located mainly outside of the P4ring plane at the λ3-phosphorus atoms but simultaneously redistributed into the P–P bond area. In addition to that, a study of its topological properties and an inspection of the Laplacian of the electron density according to Bader's `Quantum Theory of Atoms in Molecules' (QTAIM)[3] further highlight the bonding features. They reveal polar Si–N, Si–C and P–N bonds with a decreasing amount of electrostatic contribution as well as four valence shell charge concentrations (thus sp3hybridization) at each of the phosphorus atoms. Finally supported by theoretical calculations, the results illustrate the unique bonding situation in the P4unit combining a high ylidic character with unusual not exclusively sigma-like P–P bonds.

Charge density distribution in aminomethylphosphonic acid

2010 ◽  
Vol 66 (5) ◽  
pp. 559-567 ◽  
Author(s):  
Rafał Janicki ◽  
Przemysław Starynowicz
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Density Functional ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
Functional Theory ◽  
X Ray ◽  
Topological Features ◽  
Aminomethylphosphonic Acid ◽  
Experimental Charge Density

The experimental charge density distribution in aminomethylphosphonic acid has been determined from X-ray diffraction and its topological features have been analyzed. The results have shown that the P—O bonds are highly polarized, moreover the P—OH bond is weaker than the bonds to unprotonated O atoms. These facts have been confirmed by theoretical density functional theory (DFT) calculations, which have shown that the single, strongly polarized bonds within the phosphonate group are modified by hyperconjugation effects.

scholarly journals Charge density studies of energetic material: RDX

2020 ◽  
Vol 2 (1) ◽  
pp. 1-14
Author(s):  
David Stephen A ◽  
Asthana S.N ◽  
Rajesh. B. Pawar ◽  
Kumuradhas P
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Electrostatic Potential ◽  
Topological Analysis ◽  
Energetic Material ◽  
X Ray Diffraction ◽  
Explosive Material ◽  
Cyclotrimethylene Trinitramine ◽  
Density Study ◽  
Experimental Charge Density

Experimental charge density study has been carried out for Cyclotrimethylene-trinitramine (space group Pbca), an explosive material from a low temperature X-ray diffraction experiment. The electron density was modeled using the Hansen-Coppens multipole model and refined to R=0.032 for 6226 unique observed reflections. The electron density, laplacian and electrostatic potential distributions are reported and discussed, especially, the properties of the bond (3,-1) critical points, which are thought to play a key role in the decomposition of the molecule. From the bond topological analysis of all the bonds, it is observed that the N–N bond is the weakest. The dominating nature of the oxygen atoms was clearly well understood from isosurface electrostatic potential of isolated and symmetrically sitting molecules in the crystal.

scholarly journals Charge density study of N-acetyl-L-tyrosine ethyl ester monohydrate derived from CCD area detector data

1999 ◽  
Vol 55 (2) ◽  
pp. 226-230 ◽  
Author(s):  
S. Dahaoui ◽  
C. Jelsch ◽  
J. A. K. Howard ◽  
C. Lecomte
Keyword(s):  
Charge Density ◽  
Ethyl Ester ◽  
Electron Distribution ◽  
Valence Electron ◽  
X Ray Diffraction ◽  
X Ray ◽  
Area Detector ◽  
Unique Data ◽  
Thermal Vibrations ◽  
Density Study

The crystal structure, thermal vibrations and electron density of the peptide N-acetyl-L-tyrosine ethyl ester monohydrate, C13H17NO4.H2O, have been analysed using single-crystal X-ray diffraction data collected at 110 K with Mo Kα radiation to a resolution of (\sin\theta/\lambda)_\max = 1.1 Å−1. A CCD area detector was used to collect 98 393 data during one week. A multipolar atom density model was fitted against the 10 189 unique data with I > 2σ(I) [R(F) = 0.027, wR(F) = 0.020, g.o.f. = 0.65] in order to map the valence electron distribution. These deformation densities compare very well with those obtained from conventional diffractometers equipped with scintillation detectors. This work shows that area detectors permit charge density studies in a more routine way than is possible with conventional diffractometers.

Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K

2017 ◽  
Vol 73 (4) ◽  
pp. 654-659 ◽  
Author(s):  
Zhijie Chua ◽  
Bartosz Zarychta ◽  
Christopher G. Gianopoulos ◽  
Vladimir V. Zhurov ◽  
A. Alan Pinkerton
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Total Electron Density ◽  
Total Electron ◽  
Structure Factors ◽  
Density Analysis ◽  
Experimental Charge Density

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen–Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen–Coppens formalism. All intra- and intermolecular interactions have been characterized.

Experimental Charge Density Study of a Silylone

2014 ◽  
Vol 53 (10) ◽  
pp. 2766-2770 ◽  
Author(s):  
Benedikt Niepötter ◽  
Regine Herbst-Irmer ◽  
Daniel Kratzert ◽  
Prinson P. Samuel ◽  
Kartik Chandra Mondal ◽  
...  
Keyword(s):  
Charge Density ◽  
Density Study ◽  
Experimental Charge Density
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