title: Experimental versus Calculated Proton Affinities for Aromatic Carboxylic Acid Anions and Related Phenide Ions.
abstract: 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 RMSEPBE0 =1.7, RMSEB3LYP =4.6, RMSEM05-2X =6.6, RMSEG3MP2 =6.3, RMSEG4MP2 =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: RMSEPBE0 =1.9, RMSEB3LYP =4.5, RMSEM05-2X =6.3, RMSEG3MP2 =4.9, RMSEG4MP2 =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.
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland.
authors.forename: Kacper
authors.identifier: http://orcid.org/0000-0003-4852-1254
authors.initials: K
authors.lastname: Błaziak
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland.
authors.forename: Przemysław
authors.initials: P
authors.lastname: Sendys
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland. witold.danikiewicz@icho.edu.pl.
authors.forename: Witold
authors.identifier: http://orcid.org/0000-0003-0484-2689
authors.initials: W
authors.lastname: Danikiewicz
keywords: carboxylate anions; density functional calculations; phenide ions; proton affinity; quantum chemistry