Accurate calculation of N1s and C1s core electron binding energies of substituted pyridines. Correlation with basicity and with Hammett substituent constants

Author(s)

Takahata, Yuji ^[1] ; Wulfman, Carl E. ; Chong, Delano P. ^[2]

Affiliation

^[1] Univ Estadual Campinas, Dept Chem, BR-13084862 Campinas, SP - Brazil

^[2] Univ British Columbia, Dept Chem, Vancouver, BC V6T 1Z1 - Canada

• Document type: Journal article
• Source: JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM; v. 863, n. 1-3, p. 33-38, AUG 30 2008.
• Web of Science Citations: 12

Abstract

Substituent shifts of the energetics of four related ionization processes of pyridines and benzoic acids (Fig. I) were investigated. The first process is core-electron ionization of gas-phase pyridines (Fig. 1A), while the second concerns gas-phase acid-base reaction between a substituted pyridine and a Conjugated acid (Fig. 1B), and the third and fourth processes are the acid dissociation of substituted benzoic acids in aqueous solution (Fig. 1C and in vacuum (Fig. 1D), respectively. Core-electron binding energies for the first process Were Calculated using density-functional theory with the scheme Delta E-KS (PW86x-PW91c/TZP+C-ret)//HF/6-31G{*}. Average absolute deviation of calculated core electron binding energy shifts at N atom in Substituted pyridines from experiment was 0.08 eV. The shift at N coincides highly with that at a ring carbon atom. The four shifts corresponding to the four processes shown in Figs. 1A-D correlate strongly with one another. with numerical values fairly close to each other when expressed in unit of electron volts. (C) 2008 Elsevier B.V. All rights reserved. (AU)