Mechanistic insight through factors controlling effective hydrogenation of CO2 catalyzed by bioinspired proton-responsive iridium(III) complexes

Wan Hui Wang, James T. Muckerman, Etsuko Fujita, Yuichiro Himeda

Research output: Contribution to journalArticle

107 Citations (Scopus)

Abstract

Reversible H2 storage near room temperature and pressure with pH as the "switch" for controlling the direction of the reaction has been demonstrated (Nat. Chem., 2012, 4, 383-388). Several bioinspired "proton-responsive" mononuclear Ir(III) catalysts for CO2 hydrogenation were prepared to gain mechanistic insight through investigation of the factors that control the effective generation of formate. These factors include (1) kinetic isotope effects by water, hydrogen, and bicarbonate; (2) position and number of hydroxyl groups on bpy-type ligands; and (3) mono- vs dinuclear iridium complexes. We have, for the first time, obtained clear evidence from kinetic isotope effects and computational studies of the involvement of a water molecule in the rate-determining heterolysis of H 2 and accelerated proton transfer by formation of a water bridge in CO2 hydrogenation catalyzed by bioinspired complexes bearing a pendent base. Furthermore, contrary to expectations, a more significant enhancement of the catalytic activity was observed from electron donation by the ligand than on the number of the active metal centers.

Original languageEnglish
Pages (from-to)856-860
Number of pages5
JournalACS Catalysis
Volume3
Issue number5
DOIs
Publication statusPublished - May 3 2013

Keywords

  • CO hydrogenation
  • deuterium kinetic isotope effect
  • formate
  • proton relay
  • proton-responsive iridium complexes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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