Can Quantum-Mechanical Calculations Yield Reasonable Estimates of Hydrogen-Bonding Acceptor Strength? The Case of Hydrogen-Bonded Complexes of Methanol

Abstract : The thermodynamics and some vibrational properties of hydrogen-bonded complexes of methanol with 23 hydrogen-bond acceptors (HBAs) have been determined in CCl4 by FTIR spectrometry. The experimental sample contains carbon, nitrogen, oxygen, sulfur, fluorine, and chlorine organic bases and covers an energetic range of 13 kJ mol?1 in the basicity scale (??G), 22 kJ mol?1 in the affinity scale (??H), and 400 cm?1 in the spectroscopic scale (??(OH)) (from benzene to trimethylphosphane oxide and amines). The experimental results in CCl4 are compared to those computed in the gas phase at various levels of theory. Ninety five percent of the variance of the red shift and 89% of the variance of the intensification of the OH stretching upon hydrogen bonding are explained by gas-phase B3LYP/6-31+G(d,p) calculations. However, this level does not satisfactorily explain the thermodynamic properties. Only 68% of the variance of the methanol affinity (??H) is taken into account. MP2/aug-cc-pVTZ//B3LYP/6-31+G(d,p) affinity calculations raise the explanation to 77% for all HBAs and to 93% when three outliers (Me2SO, Me3PO, and tetrahydrothiophene) are excluded. Discrepancies are analyzed in terms of experimental errors, calculation approximations, and solvation.
Type de document :
Article dans une revue
Journal of Physical Chemistry A, American Chemical Society, 2011, 115 (47), pp.13975--85. 〈10.1021/jp209200w〉
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http://hal.univ-reunion.fr/hal-01188122
Contributeur : Claire Tessier <>
Soumis le : vendredi 28 août 2015 - 15:06:51
Dernière modification le : jeudi 11 janvier 2018 - 01:50:26

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Mawa Koné, Bertrand Illien, Christian Laurence, Jérôme Graton. Can Quantum-Mechanical Calculations Yield Reasonable Estimates of Hydrogen-Bonding Acceptor Strength? The Case of Hydrogen-Bonded Complexes of Methanol. Journal of Physical Chemistry A, American Chemical Society, 2011, 115 (47), pp.13975--85. 〈10.1021/jp209200w〉. 〈hal-01188122〉

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