New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis

Daria L. Huang, Rodrigo Beltrán-Suito, Julianne M. Thomsen, Sara M. Hashmi, Kelly L. Materna, Stafford W. Sheehan, Brandon Q. Mercado, Gary W Brudvig, Robert H. Crabtree

Research output: Contribution to journalArticle

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Abstract

This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp∗IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp∗Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp∗ ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp∗Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

Original languageEnglish
Pages (from-to)2427-2435
Number of pages9
JournalInorganic Chemistry
Volume55
Issue number5
DOIs
Publication statusPublished - Mar 7 2016

Fingerprint

Carbon Monoxide
Catalysis
catalysis
Oxidation
oxidation
Water
water
Chemical activation
activation
acetic acid
Acetic Acid
Isomers
isomers
Iodates
degradation
iodates
Ligands
Degradation
ligands
Propionates

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

Huang, D. L., Beltrán-Suito, R., Thomsen, J. M., Hashmi, S. M., Materna, K. L., Sheehan, S. W., ... Crabtree, R. H. (2016). New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis. Inorganic Chemistry, 55(5), 2427-2435. https://doi.org/10.1021/acs.inorgchem.5b02809

New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis. / Huang, Daria L.; Beltrán-Suito, Rodrigo; Thomsen, Julianne M.; Hashmi, Sara M.; Materna, Kelly L.; Sheehan, Stafford W.; Mercado, Brandon Q.; Brudvig, Gary W; Crabtree, Robert H.

In: Inorganic Chemistry, Vol. 55, No. 5, 07.03.2016, p. 2427-2435.

Research output: Contribution to journalArticle

Huang, DL, Beltrán-Suito, R, Thomsen, JM, Hashmi, SM, Materna, KL, Sheehan, SW, Mercado, BQ, Brudvig, GW & Crabtree, RH 2016, 'New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis', Inorganic Chemistry, vol. 55, no. 5, pp. 2427-2435. https://doi.org/10.1021/acs.inorgchem.5b02809
Huang DL, Beltrán-Suito R, Thomsen JM, Hashmi SM, Materna KL, Sheehan SW et al. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis. Inorganic Chemistry. 2016 Mar 7;55(5):2427-2435. https://doi.org/10.1021/acs.inorgchem.5b02809
Huang, Daria L. ; Beltrán-Suito, Rodrigo ; Thomsen, Julianne M. ; Hashmi, Sara M. ; Materna, Kelly L. ; Sheehan, Stafford W. ; Mercado, Brandon Q. ; Brudvig, Gary W ; Crabtree, Robert H. / New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis. In: Inorganic Chemistry. 2016 ; Vol. 55, No. 5. pp. 2427-2435.
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abstract = "This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp∗IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp∗Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp∗ ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp∗Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.",
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AU - Materna, Kelly L.

AU - Sheehan, Stafford W.

AU - Mercado, Brandon Q.

AU - Brudvig, Gary W

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N2 - This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp∗IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp∗Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp∗ ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp∗Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

AB - This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp∗IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp∗Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp∗ ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp∗Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

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