scholarly journals Topological Analysis of the Electron Density Distribution of Bis(diiminosuccinonitrilo)nickel, Ni(C4N4H2)2:  Comparison between Experiment and Theory

1998 ◽  
Vol 102 (21) ◽  
pp. 3726-3731 ◽  
Author(s):  
Tsong-Song Hwang ◽  
Yu Wang
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Topological Analysis

scholarly journals Two Tautomers of Thiobarbituric Acid in One Crystal: The Experimental Charge Density Perspective

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 223
Author(s):  
Anita M. Grześkiewicz ◽  
Maciej Kubicki
Keyword(s):  
Hydrogen Bonds ◽  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Weak Interactions ◽  
Topological Analysis ◽  
Thiobarbituric Acid ◽  
Polymorphic Form ◽  
X Ray Diffraction ◽  
Geometrical Features

High-quality crystals of a certain polymorphic form of thiobarbituric acid containing both keto and enol tautomers in the asymmetric unit were obtained. High-resolution X-ray diffraction data up to sinθ/λ = 1.0 Å−1 were collected and subsequently successfully used for the refining of the multipolar model of electron density distribution. The use of a crystal containing both ketone and enol forms allowed a direct comparison of the topological analysis results and a closer look at the differences between these two forms. The similarities and differences between the deformation densities, electrostatic potentials, Laplacian maps and bond characteristics of the tautomers were analysed. Additionally, the spectrum of the intermolecular interactions was identified and studied from classical, relatively strong N-H···O and O-H···O hydrogen bonds through weaker N-H···S hydrogen bonds to weak interactions (for instance, C-H···O, C-H···S and N···O). The results of these studies point toward the importance of including both the geometrical features and the details of the electron density distribution in the analysis of such weak interactions.

Multipole refinement and electron density analysis in natural borosilicate datolite using X-ray diffraction data

2007 ◽  
Vol 63 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Yu. V. Ivanov ◽  
E. L. Belokoneva
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Diffraction Data ◽  
Electron Density Distribution ◽  
Topological Analysis ◽  
Physical Property ◽  
Closed Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Covalent Component

The electron density distribution in the layer silicate datolite, Ca[BOH(SiO4)], was analyzed using high-precision single-crystal X-ray diffraction data (Mo Kα, T = 293 K). The Hansen–Coppens multipole model and Bader's topological analysis of the electron density provides a basis for the quantitative characterization of the bonded interaction of datolite. The results are presented both in the form of maps of the electron density distribution and its Laplacian, and in a compact way in terms of the critical points of the electron density. The relative electronegativities are also discussed. It was shown that closed-shell type interactions exist between Ca and O atoms, whereas Si—O and B—O bonds exhibit an intermediate nature with a strong covalent component. An analysis of the topology of the electrostatic potential demonstrates the relevance of considering this physical property to obtain a complete picture of structure-forming factors.

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