Theoretical Study of the Tautomerism of Substituted Azaphospholes

Abstract

The heats of formation, АН"'; ‚Беа!s оЁ tautomerization, 6AH°t; dipole moments, and vertical ionization potentials of sixteen 2-, 4-, and 5-substituted 1,3-azaphospholes and the parent compound itself were calculated for isolated molecules and for molecules embedded into a dielectric medium, using semiempirical АМI parametrization. Methyl-, carboxy-, formoxy-, and nitrogroups were used as substituents to azaphosphole ring carbon atoms. The solvent effect of dielectric medium was modelled by the seli-consistent reaction field technique. The NH-form is predicted to be the predominant tautomer for all compounds in both media studied. However, in low dielectric media other tautomers may be present in some amount which can lead to alterations of reaction mechanisms in these media.