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Title: CO 2 Hydrogenation and Formic Acid Dehydrogenation Using Ir Catalysts with Amide-Based Ligands

Abstract

In this work, a series of Ir catalysts bearing amide-based ligands generated by a deprotonated amide moiety was prepared with the hypotheses that the strong electron-donating ability of the coordinated anionic nitrogen atom and the proton-responsive OH group near the metal center will improve the catalytic activity for CO 2 hydrogenation and formic acid (FA) dehydrogenation. The effects of the modifications of the ligand architecture on the catalytic activity were investigated for CO 2 hydrogenation at ambient conditions (25 °C with 0.1 MPa H 2/CO 2 (v/v = 1/1)) and under slightly harsher conditions (50 °C with 1.0 MPa H 2/CO 2) in basic aqueous solutions together with deuterium kinetic isotope effects (KIEs) with selected catalysts. Cp*Ir( L12)(H 2O)HSO 4 ( L12 = 6-hydroxy- N-phenylpicolinamidate) that has an anionic coordinating N atom and an OH group in the second coordination sphere, exhibits a turnover frequency (TOF) of 198 h –1 based on the initial 1 h of reaction. This TOF which, to the best of our knowledge, is the highest value ever reported under ambient conditions in basic aqueous solutions. However, Cp*Ir( L10)(H 2O)HSO 4 ( L10 = (4-hydroxy- N-methylpicolinamidate) performs better in long-term CO 2 hydrogenation (up to amore » TON of 14 700 with [Ir] = 10 μM after 348 h and the final formate concentration of 0.643 M with [Ir] = 250 μM) at ambient conditions. Further, the catalytic activity for FA dehydrogenation was examined under three different conditions (pH 1.6, 2.3, and 3.5). The Cp*Ir( L12)(H 2O)HSO 4 complex in any of these conditions is less active compared to the picolinamidate catalysts without ortho-OH, owing to its instability. The complex without OH group, Cp*Ir( L8)(H 2O)HSO 4 ( L8 = N-phenyl-picolinamidate), exhibits a high TOF (up to 118 000 h -1) at 60 °C. Theoretical calculations were performed to examine the catalytic mechanism, and a step-by-step mechanism has been proposed for both CO 2 hydrogenation and FA dehydrogenation reactions. Density functional theory calculations of [Cp*Ir( L3)(H 2O)]HSO 4 ( L3 = picolinamidate) and the X-ray structure of the [Cp*Ir( L7)(H)]·H 2O ( L7 = N-methylpicolinamidate) complex imply a pH-dependent conformational change from N, N coordination to N, O coordination upon lowering the pH of the aqueous solution.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [1]
  1. National Inst. of Advanced Industrial Science and Technology, Tsukuba, Ibaraki (Japan). Dept. of Energy and Environment, Research Inst. of Energy Frontier
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. City Univ. of New York (CUNY), NY (United States). Baruch College. Dept. of Natural Science
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); Japan Science and Technology Agency (JST); Japan Society for the Promotion of Science (JSPS)
OSTI Identifier:
1599293
Report Number(s):
BNL-213622-2020-JAAM
Journal ID: ISSN 0276-7333
Grant/Contract Number:  
SC0012704; JPMJCR1342; 18K14267
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Organometallics
Additional Journal Information:
Journal Volume: 39; Journal Issue: 9; Journal ID: ISSN 0276-7333
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Catalysts; Catalytic activity; Transition metals; Ligands; Organic reactions

Citation Formats

Kanega, Ryoichi, Ertem, Mehmed Z., Onishi, Naoya, Szalda, David J., Fujita, Etsuko, and Himeda, Yuichiro. CO2 Hydrogenation and Formic Acid Dehydrogenation Using Ir Catalysts with Amide-Based Ligands. United States: N. p., 2020. Web. doi:10.1021/acs.organomet.9b00809.
Kanega, Ryoichi, Ertem, Mehmed Z., Onishi, Naoya, Szalda, David J., Fujita, Etsuko, & Himeda, Yuichiro. CO2 Hydrogenation and Formic Acid Dehydrogenation Using Ir Catalysts with Amide-Based Ligands. United States. doi:10.1021/acs.organomet.9b00809.
Kanega, Ryoichi, Ertem, Mehmed Z., Onishi, Naoya, Szalda, David J., Fujita, Etsuko, and Himeda, Yuichiro. Wed . "CO2 Hydrogenation and Formic Acid Dehydrogenation Using Ir Catalysts with Amide-Based Ligands". United States. doi:10.1021/acs.organomet.9b00809.
@article{osti_1599293,
title = {CO2 Hydrogenation and Formic Acid Dehydrogenation Using Ir Catalysts with Amide-Based Ligands},
author = {Kanega, Ryoichi and Ertem, Mehmed Z. and Onishi, Naoya and Szalda, David J. and Fujita, Etsuko and Himeda, Yuichiro},
abstractNote = {In this work, a series of Ir catalysts bearing amide-based ligands generated by a deprotonated amide moiety was prepared with the hypotheses that the strong electron-donating ability of the coordinated anionic nitrogen atom and the proton-responsive OH group near the metal center will improve the catalytic activity for CO2 hydrogenation and formic acid (FA) dehydrogenation. The effects of the modifications of the ligand architecture on the catalytic activity were investigated for CO2 hydrogenation at ambient conditions (25 °C with 0.1 MPa H2/CO2 (v/v = 1/1)) and under slightly harsher conditions (50 °C with 1.0 MPa H2/CO2) in basic aqueous solutions together with deuterium kinetic isotope effects (KIEs) with selected catalysts. Cp*Ir(L12)(H2O)HSO4 (L12 = 6-hydroxy-N-phenylpicolinamidate) that has an anionic coordinating N atom and an OH group in the second coordination sphere, exhibits a turnover frequency (TOF) of 198 h–1 based on the initial 1 h of reaction. This TOF which, to the best of our knowledge, is the highest value ever reported under ambient conditions in basic aqueous solutions. However, Cp*Ir(L10)(H2O)HSO4 (L10 = (4-hydroxy-N-methylpicolinamidate) performs better in long-term CO2 hydrogenation (up to a TON of 14 700 with [Ir] = 10 μM after 348 h and the final formate concentration of 0.643 M with [Ir] = 250 μM) at ambient conditions. Further, the catalytic activity for FA dehydrogenation was examined under three different conditions (pH 1.6, 2.3, and 3.5). The Cp*Ir(L12)(H2O)HSO4 complex in any of these conditions is less active compared to the picolinamidate catalysts without ortho-OH, owing to its instability. The complex without OH group, Cp*Ir(L8)(H2O)HSO4 (L8 = N-phenyl-picolinamidate), exhibits a high TOF (up to 118 000 h-1) at 60 °C. Theoretical calculations were performed to examine the catalytic mechanism, and a step-by-step mechanism has been proposed for both CO2 hydrogenation and FA dehydrogenation reactions. Density functional theory calculations of [Cp*Ir(L3)(H2O)]HSO4 (L3 = picolinamidate) and the X-ray structure of the [Cp*Ir(L7)(H)]·H2O (L7 = N-methylpicolinamidate) complex imply a pH-dependent conformational change from N,N coordination to N,O coordination upon lowering the pH of the aqueous solution.},
doi = {10.1021/acs.organomet.9b00809},
journal = {Organometallics},
issn = {0276-7333},
number = 9,
volume = 39,
place = {United States},
year = {2020},
month = {2}
}

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