Table 5.
Computed free energies for the isomerization process at 298K (UB3LYP/6-31G**//PCM correction, kcal/mol) relative to a1 for the a1→a5 transformation (free energies of activation are displayed in italics).
| Isomerization | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| a1→a2 | a2→a3 | a3→a4 | a4→a5 | ||||||
| Entry | ΔG‡ | ΔG | ΔG‡ | ΔG | ΔG‡ | ΔG | ΔG‡ | ΔG | |
| 1 | Y = Ph, R = Me | 8.8 | 1.4 | 12.1 | -[a] | - | −8.4 | 3.5 | −2.7 |
| 2 | Y = 2-thienyl, R = Me | 5.6 | 1.4 | 15.4 | 0.6 | 3.6 | −7.8 | 1.5 | −0.6 |
| 3 | Y = (E)-cinnamyl, R = Me | 0.1 | 2.3 | 17.8 | -[a] | - | −5.5 | 2.4 | 0.2 |
| 4 | Y = 4-MeO-C6H4, R = Me | 10.3 | 2.6 | 18.6 | −0.9 | 4.0 | −7.0 | 4.7 | −1.4 |
| 5 | Y = TMP, R = Me | 9.0 | −0.6 | 19.1 | 1.0 | 4.8 | −6.4 | 1.4 | 2.0 |
| 6 | Y = TMP, R = Et | 9.3 | −6.1 | 24.6 | 0.8 | 2.4 | −5.4 | 6.8 | 3.0 |
| 7 | Y = TMP, R = iPr | 7.9 | 5.1 | -[b] | −0.6 | 1.8 | −7.6 | 8.9 | −0.8 |
[a]
No convergence of this intermediate, direct collapse to the next one.
[b]
Could not be located on the PES.