Table 7. Gibbs Free Energies of Complexation (in kcal mol–1), Equilibrium Constants, and Maxwell–Boltzmann Distribution (%) in Water at pH = 7.4.
| Species | Forma | Site | ΔG | Ki | M-B | |
|---|---|---|---|---|---|---|
| His– | mono | uni | C11 | –0.8 | 3.86 × 10° | 0.49 |
| C12 | –1.6 | 1.39 × 101 | 1.78 | |||
| bi | C11C12 | –3.9 | 7.38 × 102 | 94.68 | ||
| bis | C11C12 | –1.9 | 2.37 × 101 | 3.04 | ||
| His2– | mono | uni | C11b | - | - | - |
| C12 | –20.6 | 1.35 × 1015 | 0.00 | |||
| bi | C11–C12 | –27.3 | 9.79 × 1019 | 0.00 | ||
| bis | C11–C12 | –45.1 | 1.18 × 1033 | 100.00 | ||
a
The nomenclature follows standard coordination chemistry conventions.
b
The complex does not form. Instead, it optimizes into the C4” form.