Charge-density analysis of 1-nitroindoline: refinement quality using free<i>R</i>factors and restraints

Zarychta, Bartosz; Zaleski, Jacek; Kyzioł, Janusz B.; Daszkiewicz, Z.; Jelsch, Christian

doi:10.1107/s0108768111013140

Cited by 36 publications

(33 citation statements)

References 50 publications

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“…The measurements were performed on the single crystals along the direction of stacking. [22] To pological bond orders were based on the XRD densities and were calculated using Equation (1): [23] [20] Multipolar refinement was carried out vs. all reflections F 2 *2 up to s = 0.95 À1 with program package MoPro.…”

Section: Methodsmentioning

confidence: 99%

Pancake Bonding in π‐Stacked Trimers in a Salt of Tetrachloroquinone Anion

Molčanov

Mou

Kertész

et al. 2018

Chemistry A European J

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The crystal structure of [4-damp]) [Cl Q] (4-damp=4-dimethylamino-N-methylpyridinium, Cl Q=tetrachloroquinone) salt is built up from slipped columnar stacks of quinoid rings composed of closely bound trimers with the intra-trimer separation distance of 2.84 Å and total charge of -2 whereas the inter-trimer distance is 3.59 Å. The individual rings exhibit partial negative charges that are distributed unevenly among the three Cl Qs in the trimer. The strong interactions within a trimer (Cl Q) have a partially covalent character with two-electron/multicentered bonding, that is extended over three rings, plausibly termed as "pancake bonding". The electron pairing within this multicentre bond leads to the fact that the crystals are diamagnetic and act as insulators. The studies of the structure and nature of bonding are based on X-ray charge density analysis and density functional theory.

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Section: Methodsmentioning

confidence: 99%

Pancake Bonding in π‐Stacked Trimers in a Salt of Tetrachloroquinone Anion

Molčanov

Mou

Kertész

et al. 2018

Chemistry A European J

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“…Topological bond orders were calculated using the formula [61] ntopo = a + bλ3 + c(λ1 + λ2) + dρcp .…”

Section: Experimental Preparationmentioning

confidence: 99%

Malleable Electronic Structure of Chloranilic Acid and Its Species Determined by X-ray Charge Density Studies

Vuković

Molčanov

Jelsch

et al. 2019

Crystal Growth & Design

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Electronic structure of five species of chloranilic acid (neutral molecule, mono-and dianion, and two chelating modes-bidendate and (bis)bidentate) is determined by X-ray charge density studies. Electron density at the bond critical points yields an accurate measure of bond order and therefore electron delocalisation. π-electron system of chloranilic acid is especially malleable, so it can adopt various degrees of delocalisation, depending on ionisation and molecular environment. 2 ABSTRACT Herein, we present a detailed X-ray charge density study of the electron delocalisation in five species of the chloranilic acid: neutral molecule, mono-and dianion, and two chelating modes-bidendate and (bis)bidentate. The experiments provide the electron density at the bond critical points, which yields an accurate measure of bond order (and therefore electron delocalisation), and complements previous literature and our data on bond lengths extracted from crystal structures and infrared spectra. Mapping of the electrostatic potential indicates electronrich and electron-poor areas in the molecule, corresponding to single (electron-poor), double and delocalised bonds (electron-rich) that can explain stacking interactions of quinoid rings in crystal packing.

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“…The R free approach, recently introduced into chargedensity analysis by Zarychta et al (2011) andPaul et al (2011), would be a very useful tool to be utilized here. Almost all of them are statistically insignificant and equal to zero, except for the P 40 of the C1 atom (the parameter value is greater than 4).…”

Section: Multipolar Parametersmentioning

confidence: 99%

Statistical analysis of multipole-model-derived structural parameters and charge-density properties from high-resolution X-ray diffraction experiments

et al. 2013

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A comprehensive analysis of various properties derived from multiple high-resolution X-ray diffraction experiments is reported. A total of 13 charge-density-quality data sets of α-oxalic acid dihydrate (C2H2O4·2H2O) were subject to Hansen-Coppens-based modelling of electron density. The obtained parameters and properties were then statistically analysed yielding a clear picture of their variability across the different measurements. Additionally, a computational approach (CRYSTAL and PIXEL programs) was utilized to support and examine the experimental findings. The aim of the study was to show the real accuracy and interpretation limits of the charge-density-derived data. An investigation of raw intensities showed that most of the reflections (60-70%) fulfil the normality test and the lowest ratio is observed for weak reflections. It appeared that unit-cell parameters are determined to the order of 10(-3) Å (for cell edges) and 10(-2) ° (for angles), and compare well with the older studies of the same compound and with the new 100 K neutron diffraction data set. Fit discrepancy factors are determined within a 0.5% range, while the residual density extrema are about ±0.16 (3) e Å(-3). The geometry is very well reproducible between different data sets. Regarding the multipole model, the largest errors are present on the valence shell charge-transfer parameters. In addition, symmetry restrictions of multipolar parameters, with respect to local coordinate systems, are well preserved. Standard deviations for electron density are lowest at bond critical points, being especially small for the hydrogen-bonded contacts. The same is true for kinetic and potential energy densities. This is also the case for the electrostatic potential distribution, which is statistically most significant in the hydrogen-bonded regions. Standard deviations for the integrated atomic charges are equal to about 0.1 e. Dipole moments for the water molecule are comparable with the ones presented in various earlier studies. The electrostatic energies should be treated rather qualitatively. However, they are quite well correlated with the PIXEL results.

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Charge-density analysis of 1-nitroindoline: refinement quality using freeRfactors and restraints

Cited by 36 publications

References 50 publications

Pancake Bonding in π‐Stacked Trimers in a Salt of Tetrachloroquinone Anion

Pancake Bonding in π‐Stacked Trimers in a Salt of Tetrachloroquinone Anion

Malleable Electronic Structure of Chloranilic Acid and Its Species Determined by X-ray Charge Density Studies

Statistical analysis of multipole-model-derived structural parameters and charge-density properties from high-resolution X-ray diffraction experiments

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