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Experimental versus Calculated Proton Affinities for Aromatic Carboxylic Acid Anions and Related Phenide Ions
Author(s) -
Błaziak Kacper,
Sendys Przemysław,
Danikiewicz Witold
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201501101
Subject(s) - carboxylate , chemistry , proton affinity , affinities , proton , ion , density functional theory , computational chemistry , quantum chemistry , quantum chemical , basis set , molecule , stereochemistry , organic chemistry , protonation , physics , supramolecular chemistry , quantum mechanics
Herein, we present the comparison of a large set of experimentally measured proton affinity (PA) values for 65 aromatic carboxylate anions with the values calculated by using selected popular DFT (B3LYP, PBE0, and M05‐2X) and composite [G3(MP2), G4(MP2)] quantum chemistry methods. The root‐mean‐square error ( RMSE ) values for the chosen methods are RMSE PBE0 =1.7, RMSE B3LYP =4.6, RMSE M05‐2X =6.6, RMSE G3MP2 =6.3, RMSE G4MP2 =4.5 kJ mol −1 . In the second part of the study, 82 PA values for substituted phenide ions and a few heteroaromatic anions were calculated. Again, very good agreement between the calculated and experimental values has been observed: RMSE PBE0 =1.9, RMSE B3LYP =4.5, RMSE M05‐2X =6.3, RMSE G3MP2 =4.9, RMSE G4MP2 =5.5 kJ mol −1 . Our results show that, for medium‐sized carboxylate anions, all tested methods give reliable results and, surprisingly, much more computationally demanding composite methods do not perform significantly better than the time‐efficient DFT methods.