1. Coupling of molecular orientation with the hydrogen-bond dimensions and H-sites in carboxylic acids
- Author
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Ratajczak-Sitarz, Małgorzata and Katrusiak, Andrzej
- Subjects
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MOLECULAR association , *HYDROGEN bonding , *CARBOXYLIC acids , *PROTON transfer reactions , *X-ray diffraction , *MOLECULAR structure , *DIMERS , *STATISTICAL correlation - Abstract
Abstract: The location of H-atoms sites in carboxylic-acid dimers has been related to the crystal environment. It has been shown that the H-sites are coupled to the orientation of carboxylic-acid groups. Consequently, the H-bonds can be strained and the H-atoms destabilized and disordered by the symmetric crystal environment of symmetric molecules. The coupling results in the O⋯O distance contraction by about 0.015Å in carboxylic acids with disordered H-atoms, this magnitude calculated from H-bonds strain being consistent with that observed in crystal structures. This strain analysis provides an easy method of locating the H-atoms in hydrogen bonds between carboxyl groups, verifying experimental data determined by X-ray diffraction, calculating the magnitudes of O⋯O distance contraction and molecular reorientations induced by the H-atoms disordering structural effects, and predicting properties related to the H-atom dynamics. The survey of carboxylic-acid structures corroborates the effects of the molecular environment on the H-sites and hydrogen-bond dimensions. [Copyright &y& Elsevier]
- Published
- 2011
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