Table 2. Thermodynamic (ΔG) and Kinetic (ΔG*) Barriers Calculated for DEA Degradation Reactions of Anion Radical Uracil Derivativesa.
| thermodynamics, ΔG |
activation barriers, ΔG* |
||||||
|---|---|---|---|---|---|---|---|
| substance | degradation path | G2MP2 | M06-2X | B3LYP | G2MP2 | M06-2X | B3LYP |
| SU | C–O (path A) | –12.1 | –7.7b | –12.4 | 11.1 | 10.4b | 11.7 |
| O–S (path B) | –17.4 | –39.4b | –42.6 | 7.5 | 2.3b | 0.96 | |
| SCNU | C–S (path A) | 3.6 | –1.6c | –3.7d | 7.9 | 8.7c | 3.4d |
| S–C (path B) | –12.1 | –16.2c | – | 1.6 | 4.1c | – | |
| BrU | C–Br (path A) | –7.5 | – | –8.0e | 1.8 | – | 2.5e |
a
All values given in kcal/mol. All calculations conducted with use of the PCM solvation model; for DFT methods 6-31++G(d,p) basis set was used.
b
Calculated for 1-methyl-5-sulfamateuracil (MeOSOU).
c
Calculated for 5-thiocyanato-2′-deoxyuridine (SCNdU).46
d
Calculated for 1-methyl-5-thiocyanatouracil (MetSCNU).
e
Calculated for 5-bromo-1-methyluracil (MetBrU).