Atomic properties and chemical bonding in the pyrite and marcasite polymorphs of FeS2: a combined experimental and theoretical electron density study

2014 ◽  
Vol 5 (4) ◽  
pp. 1408-1421 ◽  
Author(s):  
Mette S. Schmøkel ◽  
Lasse Bjerg ◽  
Simone Cenedese ◽  
Mads R. V. Jørgensen ◽  
Yu-Sheng Chen ◽  
...  
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Chemical Bonding ◽  
Atomic Properties ◽  
Density Analysis ◽  
Density Study

The chemical bonding in the pyrite (left) and marcasite (right) polymorphs of FeS2is investigated by charge density analysis.

Exploring the rare S—H...S hydrogen bond using charge density analysis in isomers of mercaptobenzoic acid

2017 ◽  
Vol 73 (4) ◽  
pp. 626-633 ◽  
Author(s):  
Mysore. S Pavan ◽  
Sounak Sarkar ◽  
Tayur N. Guru Row
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Charge Density ◽  
Interaction Energy ◽  
Electron Density ◽  
Type I ◽  
Weak Hydrogen Bond ◽  
Topological Features ◽  
Density Analysis ◽  
Density Study

Experimental and theoretical charge density analyses on isomers of mercaptobenzoic acid have been carried out to quantify the hydrogen bonding of the hitherto less explored thiols, to assess the strength of the interactions using the topological features of the electron density. The electron density study offers interesting insights into the nature of the S—H...S interaction. The interaction energy is comparable with that of a weak hydrogen bond. The strength and directionality of the S—H...S hydrogen bond is demonstrated to be mainly due to the conformation locking potential of the intramolecular S...O chalcogen bond in 2-mercaptobenzoic acid and is stronger than in 3-mercaptobenzoic acid, which lacks the intramolecular S...O bond. Thepara-substituted mercaptobenzoic acid depicts a type I S...S interaction.

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.

scholarly journals Exploring charge density analysis in crystals at high pressure: data collection, data analysis and advanced modelling

2017 ◽  
Vol 73 (4) ◽  
pp. 584-597 ◽  
Author(s):  
Nicola Casati ◽  
Alessandro Genoni ◽  
Benjamin Meyer ◽  
Anna Krawczuk ◽  
Piero Macchi
Keyword(s):  
High Pressure ◽  
Density Distribution ◽  
Charge Density ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Theoretical Work ◽  
Specific Information ◽  
Collection Data ◽  
Modelling Techniques ◽  
Density Analysis

The possibility to determine electron-density distribution in crystals has been an enormous breakthrough, stimulated by a favourable combination of equipment for X-ray and neutron diffraction at low temperature, by the development of simplified, though accurate, electron-density models refined from the experimental data and by the progress in charge density analysis often in combination with theoretical work. Many years after the first successful charge density determination and analysis, scientists face new challenges, for example: (i) determination of the finer details of the electron-density distribution in the atomic cores, (ii) simultaneous refinement of electron charge and spin density or (iii) measuring crystals under perturbation. In this context, the possibility of obtaining experimental charge density at high pressure has recently been demonstrated [Casatiet al.(2016).Nat. Commun.7, 10901]. This paper reports on the necessities and pitfalls of this new challenge, focusing on the speciessyn-1,6:8,13-biscarbonyl[14]annulene. The experimental requirements, the expected data quality and data corrections are discussed in detail, including warnings about possible shortcomings. At the same time, new modelling techniques are proposed, which could enable specific information to be extracted, from the limited and less accurate observations, like the degree of localization of double bonds, which is fundamental to the scientific case under examination.

X-ray charge density study of chemical bonding in skutteruditeCoSb3

2007 ◽  
Vol 76 (6) ◽  
Author(s):  
Atsuko Ohno ◽  
Satoshi Sasaki ◽  
Eiji Nishibori ◽  
Shinobu Aoyagi ◽  
Makoto Sakata ◽  
...  
Keyword(s):  
Charge Density ◽  
Chemical Bonding ◽  
X Ray ◽  
Density Study

Topological analysis of electron density and the electrostatic properties of isoniazid: an experimental and theoretical study

2014 ◽  
Vol 70 (2) ◽  
pp. 331-341 ◽  
Author(s):  
Gnanasekaran Rajalakshmi ◽  
Venkatesha R. Hathwar ◽  
Poomani Kumaradhas
Keyword(s):  
Hydrogen Bonding ◽  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Bond Critical Point ◽  
Potential Region ◽  
Electrostatic Properties ◽  
Structural And Electronic Properties ◽  
Density Analysis ◽  
Mycobacterial Cell Wall

Isoniazid (isonicotinohydrazide) is an important first-line antitubercular drug that targets the InhA enzyme which synthesizes the critical component of the mycobacterial cell wall. An experimental charge-density analysis of isoniazid has been performed to understand its structural and electronic properties in the solid state. A high-resolution single-crystal X-ray intensity data has been collected at 90 K. An aspherical multipole refinement was carried out to explore the topological and electrostatic properties of the isoniazid molecule. The experimental results were compared with the theoretical charge-density calculations performed usingCRYSTAL09with the B3LYP/6-31G** method. A topological analysis of the electron density reveals that the Laplacian of electron density of the N—N bond is significantly less negative, which indicates that the charges at the b.c.p. (bond-critical point) of the bond are least accumulated, and so the bond is considered to be weak. As expected, a strong negative electrostatic potential region is present in the vicinity of the O1, N1 and N3 atoms, which are the reactive locations of the molecule. The C—H...N, C—H...O and N—H...N types of intermolecular hydrogen-bonding interactions stabilize the crystal structure. The topological analysis of the electron density on hydrogen bonding shows the strength of intermolecular interactions.

A First Experimental Electron Density Study on a C70 Fullerene: (C70C2F5)10

2010 ◽  
Vol 65 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roman Kalinowski ◽  
Manuela Weber ◽  
Sergey I. Troyanov ◽  
Carsten Paulmann ◽  
Peter Luger
Keyword(s):  
High Resolution ◽  
Electron Density ◽  
Theoretical Calculations ◽  
Asymmetric Unit ◽  
Data Set ◽  
X Ray ◽  
Atomic Properties ◽  
Density Methods ◽  
Experimental Electron Density ◽  
Density Study

The electron density of the C70 fullerene C70(C2F5)10 was determined from a high-resolution X-ray data set measured with synchrotron radiation (beamline F1 of Hasylab/DESY, Germany) at a temperature of 100 K. With 140 atoms in the asymmetric unit this fullerene belongs to the largest problems examined until now by electron density methods. Using the QTAIM formalism quantitative bond topological and atomic properties have been derived and compared with the results of theoretical calculations on the title compound and on free C70

Fourier Methods and Maximum Entropy Enhancement

1997 ◽  
Author(s):  
Philip Coppens
Keyword(s):  
Fourier Transform ◽  
Charge Density ◽  
Electron Density ◽  
Complex Structure ◽  
Image Formation ◽  
Crystal Structure Analysis ◽  
Space Groups ◽  
Inverse Fourier Transformation ◽  
Density Analysis ◽  
The Fourier Transform

Image formation in diffraction is no different from image formation in other branches of optics, and it obeys the same mathematical equations. However, the nonexistence of lenses for X-ray beams makes it necessary to use computational methods to achieve the Fourier transform of the diffraction pattern into the image. The phase information required for this process is, in general, not available from the diffraction experiment, even though progress has been made in deriving phases from multiple-beam effects. This is the phase problem, the paramount issue in crystal structure analysis, which also affects charge density analysis of noncentrosymmetric structures. For centrosymmetric space groups, the independent-atom model is a sufficiently close approximation to allow calculation of the signs for all but a few very weak reflections. Images of the charge density are indispensable for qualitative understanding of chemical bonding, and play a central role in charge density analysis. In this chapter, we will discuss methods for imaging the experimental charge density, and define the functions used in the imaging procedure. According to Eq. (1.22), the structure factor F(H) is the Fourier transform of the electron density ρ(r) in the crystallographic unit cell. The electron density p(r) is then obtained by the inverse Fourier transformation, or . . . ρ(r)=∫F(H) exp (−2πi H ·r) dH (5.1) . . . in which F(H) are the (complex) structure factors corrected for the anomalous scattering discussed in chapter 1.

scholarly journals Experimental and theoretical charge-density analysis of 1,4-bis(5-hexyl-2-thienyl)butane-1,4-dione: applications of a virtual-atom model

2016 ◽  
Vol 72 (1) ◽  
pp. 75-86 ◽  
Author(s):  
Maqsood Ahmed ◽  
Ayoub Nassour ◽  
Sajida Noureen ◽  
Claude Lecomte ◽  
Christian Jelsch
Keyword(s):  
Solar Cells ◽  
Charge Density ◽  
Electron Density ◽  
Organic Solar Cells ◽  
Charge Densities ◽  
Atom Model ◽  
Residual Electron Density ◽  
Derived Properties ◽  
Density Values ◽  
Density Analysis

The experimental and theoretical charge densities of 1,4-bis(5-hexyl-2-thienyl)butane-1,4-dione, a precursor in the synthesis of thiophene-based semiconductors and organic solar cells, are presented. A dummy bond charges spherical atom model is applied besides the multipolar atom model. The results show that the dummy bond charges model is accurate enough to calculate electrostatic-derived properties which are comparable with those obtained by the multipolar atom model. The refinement statistics and the residual electron density values are found to be intermediate between the independent atom and the multipolar formalisms.

[Rh(C7H8)(PPh3)Cl]: an experimental charge-density study

2008 ◽  
Vol 64 (5) ◽  
pp. 550-557 ◽  
Author(s):  
Hazel A. Sparkes ◽  
Simon K. Brayshaw ◽  
Andrew S. Weller ◽  
Judith A. K. Howard
Keyword(s):  
High Resolution ◽  
Single Crystal ◽  
Charge Density ◽  
Organometallic Complexes ◽  
Rhodium Complexes ◽  
Crystal Data ◽  
Metal Centre ◽  
Density Analysis ◽  
Density Study ◽  
Experimental Charge Density

In order to gain a deeper understanding into the bonding situation in rhodium complexes containing rhodium–carbon interactions, the experimental charge-density analysis for [Rh(C7H8)(PPh3)Cl] (1) is reported. Accurate, high-resolution (sin θ/λ = 1.08 Å−1), single-crystal data were obtained at 100 K. The results from the investigation were interesting in relation to the interactions between the rhodium metal centre and the norbornadiene fragment and illustrate the importance of such analyses in studying bonding in organometallic complexes.

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