Table 1.

The relative energies (ΔE), energies corrected for zero point vibrations (Δ(E+ZPVE)) and free energies (ΔG) of the most important anionic tautomers of uracil reported in the previous studies and compared with the results obtained in the current study. The energies and free energies (in kcal/mol) are calculated with respect to the anion of the canonical tautomer (U0).

	Δ(E+ZPVE)*	ΔE**	ΔG***
Tautomer	Gas phase	Water	Gas phase	Water
U0−	0.00	0.00	0.00	0.00
U1−	−2.63	−0.88	−2.54	−3.64
U2−	2.81	−1.09	2.81	−6.49
U3−	7.66	6.12	7.31	1.29
U4−	9.02	1.54	8.16	−5.54

^*Ref. 24.

^**Ref. 17.

^***This study.