Abstract
The aqueous electrochemistry of selected binuclear mixed-valence oxo-bridged manganese clusters has been investigated. For [MnIIIMnIV(O)2(bpy)4]3+ (1, bpy = 2,2′-bipyridyl), it was observed that there is a substantial isotope effect (kH/kD = 4.3) for its electrochemical reduction, consistent with the proton-coupled electron transfer observed previously. Studies on [MnIIIMnIV-(O)2(edda)2]- (2, edda = ethylenediamine-N,N′-diacetate) show that the E1/2 values are also pH-dependent in a manner consistent with a one-proton/one-electron (slope of 0.07 ± 0.016 V/pH, R = 0.99) mechanism, as with 1. For [MnIIIMnIV(O)2(bispicen)2] 3+ (3, bispicen = N,N′-bis(2-methylpyridyl)ethane-1,2-diamine), similar measurements indicate an EC mechanism where the electron transfer and protonation are kinetically decoupled. The current response as a function of pH was measured to determine a pKa ∼ 8.35 for [MnIII 2(O)(OH)(bispicen)2]3+. Comparison of the electrochemical properties of 1-3 suggests that the proton-coupled mechanism is facilitated by low steric demand of the ancillary ligands and high basicity of the oxo bridges.
| Original language | English |
|---|---|
| Pages (from-to) | 494-497 |
| Number of pages | 4 |
| Journal | Inorganic Chemistry |
| Volume | 30 |
| Issue number | 3 |
| Publication status | Published - 1991 |
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- Inorganic Chemistry
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Proton-coupled electron transfer in high-valent oxomanganese dimers : Role of the ancillary ligands. / Manchanda, Rajesh; Brudvig, Gary W; Brudvig, Gary W.; Crabtree, Robert H.
In: Inorganic Chemistry, Vol. 30, No. 3, 1991, p. 494-497.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Proton-coupled electron transfer in high-valent oxomanganese dimers
T2 - Role of the ancillary ligands
AU - Manchanda, Rajesh
AU - Brudvig, Gary W
AU - Brudvig, Gary W.
AU - Crabtree, Robert H.
PY - 1991
Y1 - 1991
N2 - The aqueous electrochemistry of selected binuclear mixed-valence oxo-bridged manganese clusters has been investigated. For [MnIIIMnIV(O)2(bpy)4]3+ (1, bpy = 2,2′-bipyridyl), it was observed that there is a substantial isotope effect (kH/kD = 4.3) for its electrochemical reduction, consistent with the proton-coupled electron transfer observed previously. Studies on [MnIIIMnIV-(O)2(edda)2]- (2, edda = ethylenediamine-N,N′-diacetate) show that the E1/2 values are also pH-dependent in a manner consistent with a one-proton/one-electron (slope of 0.07 ± 0.016 V/pH, R = 0.99) mechanism, as with 1. For [MnIIIMnIV(O)2(bispicen)2] 3+ (3, bispicen = N,N′-bis(2-methylpyridyl)ethane-1,2-diamine), similar measurements indicate an EC mechanism where the electron transfer and protonation are kinetically decoupled. The current response as a function of pH was measured to determine a pKa ∼ 8.35 for [MnIII 2(O)(OH)(bispicen)2]3+. Comparison of the electrochemical properties of 1-3 suggests that the proton-coupled mechanism is facilitated by low steric demand of the ancillary ligands and high basicity of the oxo bridges.
AB - The aqueous electrochemistry of selected binuclear mixed-valence oxo-bridged manganese clusters has been investigated. For [MnIIIMnIV(O)2(bpy)4]3+ (1, bpy = 2,2′-bipyridyl), it was observed that there is a substantial isotope effect (kH/kD = 4.3) for its electrochemical reduction, consistent with the proton-coupled electron transfer observed previously. Studies on [MnIIIMnIV-(O)2(edda)2]- (2, edda = ethylenediamine-N,N′-diacetate) show that the E1/2 values are also pH-dependent in a manner consistent with a one-proton/one-electron (slope of 0.07 ± 0.016 V/pH, R = 0.99) mechanism, as with 1. For [MnIIIMnIV(O)2(bispicen)2] 3+ (3, bispicen = N,N′-bis(2-methylpyridyl)ethane-1,2-diamine), similar measurements indicate an EC mechanism where the electron transfer and protonation are kinetically decoupled. The current response as a function of pH was measured to determine a pKa ∼ 8.35 for [MnIII 2(O)(OH)(bispicen)2]3+. Comparison of the electrochemical properties of 1-3 suggests that the proton-coupled mechanism is facilitated by low steric demand of the ancillary ligands and high basicity of the oxo bridges.
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M3 - Article
VL - 30
SP - 494
EP - 497
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 3
ER -