Abstract
Proton responsive ligands offer control of catalytic reactions through modulation of pH-dependent properties, second coordination sphere stabilization of transition states, or by providing a local proton source for multiproton, multielectron reactions. Two fac-[ReI(α-diimine)(CO)3Cl] complexes with α-diimine = 4,4′- (or 6,6′-) dihydroxy-2,2′-bipyridine (4DHBP and 6DHBP) have been prepared and analyzed as electrocatalysts for the reduction of carbon dioxide. Consecutive electrochemical reduction of these complexes yields species identical to those obtained by chemical deprotonation. An energetically feasible mechanism for reductive deprotonation is proposed in which the bpy anion is doubly protonated followed by loss of H2 and 2H+. Cyclic voltammetry reveals a two-electron, three-wave system owing to competing EEC and ECE pathways. The chemical step of the ECE pathway might be attributed to the reductive deprotonation but cannot be distinguished from chloride dissociation. The rate obtained by digital simulation is approximately 8 s-1. Under CO2, these competing reactions generate a two-slope catalytic waveform with onset potential of -1.65 V vs Ag/AgCl. Reduction of CO2 to CO by the [ReI(4DHBP-2H+)(CO)3]- suggests the interaction of CO2 with the deprotonated species or a third reduction followed by catalysis. Conversely, the reduced form of [Re(6DHBP)(CO)3Cl] converts CO2 to CO with a single turnover.
| Original language | English |
|---|---|
| Pages (from-to) | 7457-7466 |
| Number of pages | 10 |
| Journal | Journal of Physical Chemistry B |
| Volume | 119 |
| Issue number | 24 |
| DOIs | |
| Publication status | Published - Jun 18 2015 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Materials Chemistry
- Surfaces, Coatings and Films
Cite this
Push or Pull? Proton Responsive Ligand Effects in Rhenium Tricarbonyl CO2 Reduction Catalysts. / Manbeck, Gerald F.; Muckerman, James; Szalda, David J.; Himeda, Yuichiro; Fujita, Etsuko.
In: Journal of Physical Chemistry B, Vol. 119, No. 24, 18.06.2015, p. 7457-7466.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Push or Pull? Proton Responsive Ligand Effects in Rhenium Tricarbonyl CO2 Reduction Catalysts
AU - Manbeck, Gerald F.
AU - Muckerman, James
AU - Szalda, David J.
AU - Himeda, Yuichiro
AU - Fujita, Etsuko
PY - 2015/6/18
Y1 - 2015/6/18
N2 - Proton responsive ligands offer control of catalytic reactions through modulation of pH-dependent properties, second coordination sphere stabilization of transition states, or by providing a local proton source for multiproton, multielectron reactions. Two fac-[ReI(α-diimine)(CO)3Cl] complexes with α-diimine = 4,4′- (or 6,6′-) dihydroxy-2,2′-bipyridine (4DHBP and 6DHBP) have been prepared and analyzed as electrocatalysts for the reduction of carbon dioxide. Consecutive electrochemical reduction of these complexes yields species identical to those obtained by chemical deprotonation. An energetically feasible mechanism for reductive deprotonation is proposed in which the bpy anion is doubly protonated followed by loss of H2 and 2H+. Cyclic voltammetry reveals a two-electron, three-wave system owing to competing EEC and ECE pathways. The chemical step of the ECE pathway might be attributed to the reductive deprotonation but cannot be distinguished from chloride dissociation. The rate obtained by digital simulation is approximately 8 s-1. Under CO2, these competing reactions generate a two-slope catalytic waveform with onset potential of -1.65 V vs Ag/AgCl. Reduction of CO2 to CO by the [ReI(4DHBP-2H+)(CO)3]- suggests the interaction of CO2 with the deprotonated species or a third reduction followed by catalysis. Conversely, the reduced form of [Re(6DHBP)(CO)3Cl] converts CO2 to CO with a single turnover.
AB - Proton responsive ligands offer control of catalytic reactions through modulation of pH-dependent properties, second coordination sphere stabilization of transition states, or by providing a local proton source for multiproton, multielectron reactions. Two fac-[ReI(α-diimine)(CO)3Cl] complexes with α-diimine = 4,4′- (or 6,6′-) dihydroxy-2,2′-bipyridine (4DHBP and 6DHBP) have been prepared and analyzed as electrocatalysts for the reduction of carbon dioxide. Consecutive electrochemical reduction of these complexes yields species identical to those obtained by chemical deprotonation. An energetically feasible mechanism for reductive deprotonation is proposed in which the bpy anion is doubly protonated followed by loss of H2 and 2H+. Cyclic voltammetry reveals a two-electron, three-wave system owing to competing EEC and ECE pathways. The chemical step of the ECE pathway might be attributed to the reductive deprotonation but cannot be distinguished from chloride dissociation. The rate obtained by digital simulation is approximately 8 s-1. Under CO2, these competing reactions generate a two-slope catalytic waveform with onset potential of -1.65 V vs Ag/AgCl. Reduction of CO2 to CO by the [ReI(4DHBP-2H+)(CO)3]- suggests the interaction of CO2 with the deprotonated species or a third reduction followed by catalysis. Conversely, the reduced form of [Re(6DHBP)(CO)3Cl] converts CO2 to CO with a single turnover.
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U2 - 10.1021/jp511131x
DO - 10.1021/jp511131x
M3 - Article
VL - 119
SP - 7457
EP - 7466
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 24
ER -