Ab‐initio sto‐3G energies for uracil (U) and the tautomer 4‐hydroxyuracil (U*) are reported. The four highest occupied molecular orbital energies for uracil correlate with experimental photoelectron ionization potentials with a least‐squares linear correlation coefficient of 0.999. The energy ΔEt for U ⇋ U* using the best available geometries is 25.5 kcal/mole. The reaction field continuum model for the solvent effect indicates that ΔEt may be lowered by approximately 3 kcal/mole. Therefore the diketo form of uracil is theoretically determined to be the most stable form in solution as well as in the gas phase, in complete agreement with experiment.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Physical and Theoretical Chemistry