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A study of the energetics of formation of heterocomplexed cations formed by asymmetric O...H...O hydrogen bonding in systems of pyridine N-oxide and its derivatives using the means of restricted Hartree-Fock and Moller-Plesset ab initio calculations and the energy and Gibbs free energies of cationic heteroconjugation are calculated using the 6-31G* basis set is presented.

An investigation of the energetic of protonation of pyridine and a series of its derivatives, as well as the energetic of formation of hydrogen bonded N...H...N homocomplexed cations in systems involving substituted pyridines and conjugate cationic acids, is presented. It shows that the proton potential of a homocomplexed pyridine cation exhibits a relatively high-energy barrier even when the thermodynamic correction is included.

The article discusses research methods used to assess the energetics of pyridine N-oxide when bonded with protonation and hydrogen.

Energies and Gibbs free energies of protonation and formation of homocomplexed anions stabilized by O..H..O bridges for 10 substituted phenol systems in the gas phase were calculated using ab initio methods at the RHF and MP2 levels and the PCM model utilizing the Gaussian 6-31++G** basis set. The calculated protonation energies were found to correlate well with the acid dissociation constants in acetronitrile (AN) solutions.

Acidity constants in the polar aprotic acetonitrile of cations obtained by protonation of 13 substituted 4-nitropyridine N-oxides and cationic homoconjugation constants of the cationic acids conjugated with the N-oxides studied are determined using the potentiometric titration method.

The energies of protonation and of hydrogen-bond complex formation of neutral and protonated forms with one water molecule were studied by means of ab initio calculations for polyfunctional nitrogen 'push=pull' base, Me2N - CH = N - C triple bond N. The calculations showed that the N-cyano site is more basic that the N-amino one for both reactions, proton-transfer and hydrogen-bonding in the gas-phase.