Abstract
Dihydrogen (H2) has many desirable features as a fuel, but utilization of H2 is limited due to storage and transportation problems. A promising solution to these issues is reversible storage of hydrogen in the form of liquid-phase chemicals such as formic acid (FA), which could be accomplished by the development of efficient and robust catalysts. Recently, proton-responsive, half-sandwich CpIrIII (where Cp∗ = pentamethylcyclopentadienyl anion) complexes capable of reversible hydrogen storage via interconversion between H2/CO2 and formic acid/formate in water have been reported. This interconversion is performed via CO2 hydrogenation and FA dehydrogenation reactions and modulated by the pH of the medium. We report the results of a computational investigation of the mechanistic aspects of reversible hydrogen storage via two of these catalysts: namely, [CpIr(4DHBP)]2+ (4DHBP = 4,4′-dihydroxy-2,2′-bipyridine) and [CpIr(6DHBP)]2+ (6DHBP = 6,6′-dihydroxy-2,2′-bipyridine). Distinct features of the catalytic cycles of [CpIr(4DHBP)]2+ and [CpIr(6DHBP)]2+ for CO2 hydrogenation and FA dehydrogenation reactions are demonstrated using density functional theory (DFT) calculations employing a speciation approach and probing deuterium kinetic isotope effects (KIE). In addition to the mechanistic insights and principles for the design of improved next-generation catalysts, the validation of computational methods for the investigation of the hydrogenation and dehydrogenation reactions is addressed.
| Original language | English |
|---|---|
| Pages (from-to) | 600-609 |
| Number of pages | 10 |
| Journal | ACS Catalysis |
| Volume | 6 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Feb 5 2016 |
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Keywords
- CO hydrogenation
- density functional theory
- formic acid dehydrogenation
- hydrogen storage
- iridium complexes
- kinetic isotope effect
- proton-responsive ligand
ASJC Scopus subject areas
- Catalysis
Cite this
Interconversion of Formic Acid and Carbon Dioxide by Proton-Responsive, Half-Sandwich CpIrIII Complexes : A Computational Mechanistic Investigation. / Ertem, Mehmed Z.; Himeda, Yuichiro; Fujita, Etsuko; Muckerman, James.
In: ACS Catalysis, Vol. 6, No. 2, 05.02.2016, p. 600-609.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Interconversion of Formic Acid and Carbon Dioxide by Proton-Responsive, Half-Sandwich CpIrIII Complexes
T2 - A Computational Mechanistic Investigation
AU - Ertem, Mehmed Z.
AU - Himeda, Yuichiro
AU - Fujita, Etsuko
AU - Muckerman, James
PY - 2016/2/5
Y1 - 2016/2/5
N2 - Dihydrogen (H2) has many desirable features as a fuel, but utilization of H2 is limited due to storage and transportation problems. A promising solution to these issues is reversible storage of hydrogen in the form of liquid-phase chemicals such as formic acid (FA), which could be accomplished by the development of efficient and robust catalysts. Recently, proton-responsive, half-sandwich CpIrIII (where Cp∗ = pentamethylcyclopentadienyl anion) complexes capable of reversible hydrogen storage via interconversion between H2/CO2 and formic acid/formate in water have been reported. This interconversion is performed via CO2 hydrogenation and FA dehydrogenation reactions and modulated by the pH of the medium. We report the results of a computational investigation of the mechanistic aspects of reversible hydrogen storage via two of these catalysts: namely, [CpIr(4DHBP)]2+ (4DHBP = 4,4′-dihydroxy-2,2′-bipyridine) and [CpIr(6DHBP)]2+ (6DHBP = 6,6′-dihydroxy-2,2′-bipyridine). Distinct features of the catalytic cycles of [CpIr(4DHBP)]2+ and [CpIr(6DHBP)]2+ for CO2 hydrogenation and FA dehydrogenation reactions are demonstrated using density functional theory (DFT) calculations employing a speciation approach and probing deuterium kinetic isotope effects (KIE). In addition to the mechanistic insights and principles for the design of improved next-generation catalysts, the validation of computational methods for the investigation of the hydrogenation and dehydrogenation reactions is addressed.
AB - Dihydrogen (H2) has many desirable features as a fuel, but utilization of H2 is limited due to storage and transportation problems. A promising solution to these issues is reversible storage of hydrogen in the form of liquid-phase chemicals such as formic acid (FA), which could be accomplished by the development of efficient and robust catalysts. Recently, proton-responsive, half-sandwich CpIrIII (where Cp∗ = pentamethylcyclopentadienyl anion) complexes capable of reversible hydrogen storage via interconversion between H2/CO2 and formic acid/formate in water have been reported. This interconversion is performed via CO2 hydrogenation and FA dehydrogenation reactions and modulated by the pH of the medium. We report the results of a computational investigation of the mechanistic aspects of reversible hydrogen storage via two of these catalysts: namely, [CpIr(4DHBP)]2+ (4DHBP = 4,4′-dihydroxy-2,2′-bipyridine) and [CpIr(6DHBP)]2+ (6DHBP = 6,6′-dihydroxy-2,2′-bipyridine). Distinct features of the catalytic cycles of [CpIr(4DHBP)]2+ and [CpIr(6DHBP)]2+ for CO2 hydrogenation and FA dehydrogenation reactions are demonstrated using density functional theory (DFT) calculations employing a speciation approach and probing deuterium kinetic isotope effects (KIE). In addition to the mechanistic insights and principles for the design of improved next-generation catalysts, the validation of computational methods for the investigation of the hydrogenation and dehydrogenation reactions is addressed.
KW - CO hydrogenation
KW - density functional theory
KW - formic acid dehydrogenation
KW - hydrogen storage
KW - iridium complexes
KW - kinetic isotope effect
KW - proton-responsive ligand
UR - http://www.scopus.com/inward/record.url?scp=84957578038&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84957578038&partnerID=8YFLogxK
U2 - 10.1021/acscatal.5b01663
DO - 10.1021/acscatal.5b01663
M3 - Article
AN - SCOPUS:84957578038
VL - 6
SP - 600
EP - 609
JO - ACS Catalysis
JF - ACS Catalysis
SN - 2155-5435
IS - 2
ER -