Table 3.
Electrochemical parameters for the reduction of the experimentally accessible species of MnP complexes, [NaCl] = 0.1 M, θ = 25 °C. Values of the deprotonation constants were taken from ref. 32: pK′a1 = 11.75, pKa1 = 10.89, pKa2 = 11.62, pK″a3 = 11.14 for MnTE-2-PyP and pK′a1 = 12.04, pKa1 = 11.57, pKa2 = 12.70 and pK″a3 = 11.99 for MnTE-3-PyP. As previously in Figures 7, 8, S11 and S12, the experimentally unavailable deprotonation constants were taken to be at least one pH unit beyond the studied pH range, i.e. pK′a2 = 14, pKa3 = 14, pKa4 = 15, pK″a1 = 5, pK″a2 = 6, pK″a4 = 14.
| MnP | couple | index | Ei0′/V vs. SHE* | ki0/10−2 cm s−1 | αi |
|---|---|---|---|---|---|
| MnTE-2-PyP | MnIIIP/MnIIP | 1 | 0.145 | 0.3 | 0.4 |
| 2 | 0.094 | 0.7 | 0.3 | ||
| 3 | ≤ −0.046 | ≤ 0.3 | 0.3 | ||
| MnIVP/MnIIIP | 5 | ≥ 0.812 | 1.0 | 0.3 | |
| 6 | 0.470 | 1.3 | 0.3 | ||
| 7 | ≤ 0.301 | ≤ 1.6 | 0.4 | ||
| MnTE-3-PyP | MnIIIP/MnIIP | 1 | −0.020 | 0.4 | 0.4 |
| 2 | −0.045 | 0.8 | 0.3 | ||
| 3 | ≤ −0.121 | ≤ 0.3 | 0.3 | ||
| MnIVP/MnIIIP | 5 | ≥ 0.779 | 1.0 | 0.3 | |
| 6 | 0.390 | 1.3 | 0.3 | ||
| 7 | ≤ 0.271 | ≤ 1.4 | 0.4 |
The calculated values differ somewhat from the previously published potentials determined by cyclic voltammetry,24 due to the differences in methodology and electrode calibration. Yet, importantly, the differences in the formal reduction potentials among the studied members of Mn(III) N-alkylpyridylporphyrin series are correct and thus all relationships based on these differences are correct as well.