Molecular acidity: A quantitative conceptual density functional theory description

Accurate predictions of molecular acidity using ab initio and density functional approaches are still a daunting task. Using electronic and reactivity properties, one can quantitatively estimate pKa values of acids. In a recent paper [S. B. Liu and L. G. Pedersen, J. Phys. Chem. A 113, 3648 (2009)],...

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Bibliographic Details
Published inThe Journal of chemical physics Vol. 131; no. 16; p. 164107
Main Authors Liu, Shubin, Schauer, Cynthia K, Pedersen, Lee G
Format Journal Article
LanguageEnglish
Published United States 28.10.2009
Subjects
Acids - chemistry
Hydrogen-Ion Concentration
Models, Molecular
Molecular Conformation
Quantum Theory
Reproducibility of Results
Thermodynamics
Transition Elements - chemistry
Water - chemistry
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Summary:Accurate predictions of molecular acidity using ab initio and density functional approaches are still a daunting task. Using electronic and reactivity properties, one can quantitatively estimate pKa values of acids. In a recent paper [S. B. Liu and L. G. Pedersen, J. Phys. Chem. A 113, 3648 (2009)], we employed the molecular electrostatic potential (MEP) on the nucleus and the sum of valence natural atomic orbital (NAO) energies for the purpose. In this work, we reformulate these relationships on the basis of conceptual density functional theory and compare the results with those from the thermodynamic cycle method. We show that MEP and NAO properties of the dissociating proton of an acid should satisfy the same relationships with experimental pKa data. We employ 27 main groups and first to third row transition metal-water complexes as illustrative examples to numerically verify the validity of these strong linear correlations. Results also show that the accuracy of our approach and that of the conventional method through the thermodynamic cycle are statistically similar.
ISSN:1089-7690
DOI:10.1063/1.3251124