Table 2.
Threshold energies, E0; activation entropies, ΔS‡; and pre-exponential factors, A, for individual reaction channels of NCX
| Ligand | DCM | DGD | |||
|---|---|---|---|---|---|
| DCM2+ + H2PO4− | DCM2+ + PO3− | [DGD + H]+ | [DGD + H3PO4 + H]+ | [DGD + HPO3 + H]+ | |
| A3pSA3−NH2 | |||||
| E0, eV | 1.21 | 1.79 | 1.37 | ||
| ΔS‡, eua | 3.1 | 34 | 4.1 | ||
| A, s−1 | 1 × 1014 | 8 × 1020 | 3 × 1012 | ||
| A3pTA3−NH2 | |||||
| E0, eV | 1.47 | 1.9 | 1.86 | 1.49 | |
| ΔS‡, eu | 10 | 34 | 40 | −3.4 | |
| A, s−1 | 4 × 1015 | 9 × 1020 | 1 × 1022 | 5 × 1012 | |
| A3pYA3−NH2 | |||||
| E0, eV | 1.82 | 1.7 | 1.5 | ||
| ΔS‡, eu | 24 | 22 | −2.7 | ||
| A, s−1 | 6 × 1018 | 2 × 1018 | 7 × 1012 |
a
e.u. = entropy unit = cal mol−1 K−1; activation entropies and pre-exponential factors at 450 K. The estimated uncertainties are ±7% for the threshold energies and ±15% for the activation entropies.