Abstract
One-electron reduction and subsequent protonation of a biomimetic proton-reduction catalyst [FeFe(μ-pdt)(CO)6] (pdt = propanedithiolate), 1, were investigated by UV-vis and IR spectroscopy on a nano- to microsecond time scale. The study aimed to provide further insight into the proton-reduction cycle of this [FeFe]-hydrogenase model complex, which with its prototypical alkyldithiolate-bridged diiron core is widely employed as a molecular, precious metal-free catalyst for sustainable H2 generation. The one-electron-reduced catalyst was obtained transiently by electron transfer from photogenerated [Ru(dmb)3]+ in the absence of proton sources or in the presence of acids (dichloro- or trichloroacetic acid or tosylic acid). The reduced catalyst and its protonation product were observed in real time by UV-vis and IR spectroscopy, leading to their structural characterization and providing kinetic data on the electron and proton transfer reactions. 1 features an intact (μ2,κ2-pdt)(μ-H)Fe2 core in the reduced, 1-, and reduced-protonated states, 1H, in contrast to the Fe-S bond cleavage upon the reduction of [FeFe(bdt)(CO)6], 2, with a benzenedithiolate bridge. The driving-force dependence of the rate constants for the protonation of 1- (kpt = 7.0 × 105, 1.3 × 107, and 7.0 × 107 M-1 s-1 for the three acids used in this study) suggests a reorganization energy >1 eV and indicates that hydride complex 1H is formed by direct protonation of the Fe-Fe bond. The protonation of 1- is sufficiently fast even with the weaker acids, which excludes a rate-limiting role in light-driven H2 formation under typical conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 768-776 |
| Number of pages | 9 |
| Journal | Inorganic Chemistry |
| Volume | 57 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Jan 16 2018 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
Cite this
Structural and Kinetic Studies of Intermediates of a Biomimetic Diiron Proton-Reduction Catalyst. / Wang, Shihuai; Aster, Alexander; Mirmohades, Mohammad; Lomoth, Reiner; Hammarström, Leif.
In: Inorganic Chemistry, Vol. 57, No. 2, 16.01.2018, p. 768-776.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Structural and Kinetic Studies of Intermediates of a Biomimetic Diiron Proton-Reduction Catalyst
AU - Wang, Shihuai
AU - Aster, Alexander
AU - Mirmohades, Mohammad
AU - Lomoth, Reiner
AU - Hammarström, Leif
PY - 2018/1/16
Y1 - 2018/1/16
N2 - One-electron reduction and subsequent protonation of a biomimetic proton-reduction catalyst [FeFe(μ-pdt)(CO)6] (pdt = propanedithiolate), 1, were investigated by UV-vis and IR spectroscopy on a nano- to microsecond time scale. The study aimed to provide further insight into the proton-reduction cycle of this [FeFe]-hydrogenase model complex, which with its prototypical alkyldithiolate-bridged diiron core is widely employed as a molecular, precious metal-free catalyst for sustainable H2 generation. The one-electron-reduced catalyst was obtained transiently by electron transfer from photogenerated [Ru(dmb)3]+ in the absence of proton sources or in the presence of acids (dichloro- or trichloroacetic acid or tosylic acid). The reduced catalyst and its protonation product were observed in real time by UV-vis and IR spectroscopy, leading to their structural characterization and providing kinetic data on the electron and proton transfer reactions. 1 features an intact (μ2,κ2-pdt)(μ-H)Fe2 core in the reduced, 1-, and reduced-protonated states, 1H, in contrast to the Fe-S bond cleavage upon the reduction of [FeFe(bdt)(CO)6], 2, with a benzenedithiolate bridge. The driving-force dependence of the rate constants for the protonation of 1- (kpt = 7.0 × 105, 1.3 × 107, and 7.0 × 107 M-1 s-1 for the three acids used in this study) suggests a reorganization energy >1 eV and indicates that hydride complex 1H is formed by direct protonation of the Fe-Fe bond. The protonation of 1- is sufficiently fast even with the weaker acids, which excludes a rate-limiting role in light-driven H2 formation under typical conditions.
AB - One-electron reduction and subsequent protonation of a biomimetic proton-reduction catalyst [FeFe(μ-pdt)(CO)6] (pdt = propanedithiolate), 1, were investigated by UV-vis and IR spectroscopy on a nano- to microsecond time scale. The study aimed to provide further insight into the proton-reduction cycle of this [FeFe]-hydrogenase model complex, which with its prototypical alkyldithiolate-bridged diiron core is widely employed as a molecular, precious metal-free catalyst for sustainable H2 generation. The one-electron-reduced catalyst was obtained transiently by electron transfer from photogenerated [Ru(dmb)3]+ in the absence of proton sources or in the presence of acids (dichloro- or trichloroacetic acid or tosylic acid). The reduced catalyst and its protonation product were observed in real time by UV-vis and IR spectroscopy, leading to their structural characterization and providing kinetic data on the electron and proton transfer reactions. 1 features an intact (μ2,κ2-pdt)(μ-H)Fe2 core in the reduced, 1-, and reduced-protonated states, 1H, in contrast to the Fe-S bond cleavage upon the reduction of [FeFe(bdt)(CO)6], 2, with a benzenedithiolate bridge. The driving-force dependence of the rate constants for the protonation of 1- (kpt = 7.0 × 105, 1.3 × 107, and 7.0 × 107 M-1 s-1 for the three acids used in this study) suggests a reorganization energy >1 eV and indicates that hydride complex 1H is formed by direct protonation of the Fe-Fe bond. The protonation of 1- is sufficiently fast even with the weaker acids, which excludes a rate-limiting role in light-driven H2 formation under typical conditions.
UR - http://www.scopus.com/inward/record.url?scp=85041807639&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85041807639&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.7b02687
DO - 10.1021/acs.inorgchem.7b02687
M3 - Article
AN - SCOPUS:85041807639
VL - 57
SP - 768
EP - 776
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 2
ER -