Electronegativity is a frequently used chemical term, describing "the power of an atom in a molecule to attract electrons to itself". Application of the Domenicano et al method of estimating group electronegativity from angular geometry of the ring in monosubstituted benzene derivatives[1] allowed us to find how electronegativity of OH/O^- groups in H-bonded complexes of phenol and phenolate depends on the nature and strength of H-bond. For complexes in which the OH group is only proton donating in the H-bond a linear dependence of the estimated electronegativity on O…O(N) interatomic distance was found for experimental (CSD [2] base retrieved) data. The following rule is observed [3]: the weaker is the H-bond the more electronegative the OH group is. If apart from this kind of interaction the oxygen is proton accepting, then an increase of electronegativity is observed. Modeling (B3LYP/6-311+G**) variation of the strength of H-bond leads to a qualitatively the same picture as the scatter plots for experimental data.

[1] A. R. Campanelli, A. Domenicano, F. Ramondo, I. Hargittai, J. Phys. Chem. A 2004, 108, 4940-4948.

[2] The Cambridge Structure Database, the 5.27 version, November 2005.

[3] T. M. Krygowski, H. Szatyłowicz, J. Phys. Chem. A 2006, 110, 7232-7236.