Table 1.
Equilibrium constants and ground state thermodynamics for hydrogen atom transfer reactions in MeCN.
| AH + B | Methoda | Keq (298 K) | ΔGoHAT (kcal mol−1) | ΔHoHAT (kcal mol−1) | ΔSoHAT (cal mol−1 K−1) |
|---|---|---|---|---|---|
| FeII(H2bip) + TEMPO | VHb | 1.7 ± 0.3 | −0.3 ± 0.2 | −9.4 ± 0.6 | −30 ± 2 |
| Cal | -- | -- | −8.9 ± 0.6 | -- | |
| BDFE | ∼2 | −0.5 ± 1 | -- | -- | |
| FeII(H2bim) + TEMPO | VHb | (2.0 ± 0.3) × 10−4 | 5.0 ± 0.2 | −4.1 ± 0.3 | −30 ± 2 |
| BDFE | ∼0.9 × 10−4 | 5.5 ± 1.0 | -- | -- | |
| RuII(py-imH) + TEMPO | VHc | (1.8 ± 0.2) × 103 | −4.4 ± 0.1 | −3.0 ± 0.3 | 4.9 ± 1.1 |
| BDFE | (2.0 ± 1.5) × 103 | −4.5 ± 0.4 | -- | -- | |
| CoII(H2bim) + TEMPO | VH | (5.9 ± 0.8) × 10−3 | 3.0 ± 0.4 | −9.3 ± 0.4 | −41 ± 2 |
| BDFE | ∼0.6 | 0.3 ± 3d | -- | -- | |
| RuII(py-imH) + tBu3PhO• | BDE | -- | -- | −15 ± 1 | -- |
| RuII(hfac)2(py-imH) + tBu3PhO• | VH | 0.062 ± 0.013 | 1.6 ± 0.1 | -- | -- |
| CoII(H2bim) + tBu3PhO• | BDE | -- | -- | -24 ± 4 | -- |
| TEMPOH + tBu3PhO• | Cal | -- | -- | −11.2 ± 0.5 | -- |
| BD(F)E | -- | −10 ± 1 | −11.5 ± 1.4 | −2 ± 3 |
a
Method: VH (van't Hoff) = Temperature dependence of Keq from van't Hoff plots; Cal = calorimetric; BDFE/BDE: ΔGoHAT = BDFE[AH] - BDFE[BH] and/or ΔHoHAT = BDE[AH] - BDE[BH], using values from Table 2.
b
Data from reference 28.
c
Data from reference 32.
d
Estimated from BDFEs derived from pKa and Eo values, see Table 2.