Charge-density analysis and electrostatic properties of 2-carboxy-4-methylanilinium chloride monohydrate obtained using a multipolar and a spherical-charges model - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Acta Crystallographica Section A : Foundations and Advances [2014-...] Année : 2012

Charge-density analysis and electrostatic properties of 2-carboxy-4-methylanilinium chloride monohydrate obtained using a multipolar and a spherical-charges model

Résumé

The new crystal structure of 2-carboxy-4-methylanilinium chloride monohydrate was determined by X-ray diffraction and refined using three different electron-density models. In the first model, the ELMAM2 multipolar electron-density database was transferred to the molecule. Theoretical structure factors were also computed from periodic density functional theory calculations and yielded, after multipolar-atoms refinement, the second charge-density model. An alternative electron-density modelling, based on spherical atoms and additional charges on the covalent bonds and electron lone-pair sites, was used in the third model in the refinement versus the theoretical data. The crystallographic refinements, structural properties, electron-density distributions and molecular electrostatic potentials obtained from the different charge-density models were compared. As the number of variables refined in the different models is the same, the R factor is a good indicator of refinement quality. The R factor is best for multipolar modelling, presumably because of the greater flexibility and larger number of parameters to model the electron density compared to the spherical-charges model. The electrostatic potentials around the molecule show a high correlation coefficient between the three models.
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hal-01710504 , version 1 (16-02-2018)

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Noureddine Dadda, Ayoub Nassour, Benoit Guillot, Nourredine Benali-Cherif, Christian Jelsch. Charge-density analysis and electrostatic properties of 2-carboxy-4-methylanilinium chloride monohydrate obtained using a multipolar and a spherical-charges model. Acta Crystallographica Section A : Foundations and Advances [2014-..], 2012, A68 (4), pp.452-463. ⟨10.1107/S0108767312016571⟩. ⟨hal-01710504⟩
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