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Keywords:

  • bases;
  • basicity;
  • cationic acids;
  • density functional calculations;
  • periodic table;
  • proton affinities;
  • thermochemistry

Abstract

We have carried out an extensive exploration of the gas-phase basicity of archetypal neutral bases across the periodic system using the generalized gradient approximation (GGA) of the density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. First, we validate DFT as a reliable tool for computing proton affinities and related thermochemical quantities: BP86/QZ4P//BP86/TZ2P is shown to yield a mean absolute deviation of 2.0 kcal/mol for the proton affinity at 298 K with respect to experiment, and 1.2 kcal/mol with high-level ab initio benchmark data. The main purpose of this work is to provide the proton affinities (and corresponding entropies) at 298 K of the neutral bases constituted by all maingroup-element hydrides of groups 15–17 and the noble gases, that is, group 18, and periods 1–6. We have also studied the effect of step-wise methylation of the protophilic center of the second- and third-period bases. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1486–1493, 2006