Table 3.
Standard reduction potential (E°) values in mV relative to SHE calculated with direct and isodesmic methods, at B3LYP/cc-pVDZ and M06-2X/cc-pVTZ computational levels (T = 298.15 K). The most favourable spin states were employed (as specified in parentheses).
| Reduction Half-Reaction | ||||||
|---|---|---|---|---|---|---|
| Fe(III)-PO/Fe(II)-PO (5/2–2) |
PO-I/Fe(III)-PO (1/2–5/2) |
PO-I/PO-II (1/2–1) |
PO-I/PO-II-H (1/2–1) |
PO-II/Fe(III)-PO (1–5/2) |
PO-II-H/Fe(III)-PO (1–5/2) |
|
| Direct method | ||||||
| B3LYP/cc-pVDZ | 377 | 1066 | 741 | 1245 | 1391 | 886 |
| M06-2X/cc-pVTZ | 662 | 2358 | 1120 | 2380 | 3596 | 2336 |
| Isodesmic method | ||||||
| B3LYP/cc-pVDZ | 237 | 798 | 601 | 1105 | 1251 | 747 |
| M06-2X/cc-pVTZ | −770 | 955 | −312 | 948 | 2164 | 904 |