ملخص: Several pyridone-like compounds, where the extracyclic oxygen atom has been replaced by a sulfur atom or an imino NH group, have been studied using B3LYP/6-311+G** calculations. We found that the NH substituted species differ from the other ones: a single tautomeric form, i.e. the aminopyridine one, strongly dominates either in the gas phase or in the presence of a polar solvent like DMSO. In the gas phase or in solution, pyridinethiol species are more favoured than the pyridinol ones relatively to their corresponding tautomers. The zero point vibration energy and the entropic contribution to the free energy of the reaction play a more determining role for the sulphur containing species.

لغة: إنجليزية