Reductive Cleavage of CO2 by Metal-Ligand-Cooperation Mediated by an Iridium Pincer Complex

Moran Feller, Urs Gellrich, Aviel Anaby, Yael Diskin-Posner, David Milstein

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50 Citations (Scopus)


A unique mode of stoichiometric CO2 activation and reductive splitting based on metal-ligand-cooperation is described. The novel Ir hydride complexes [(tBu-PNP)Ir(H)2] (2) (tBu-PNP, deprotonated tBu-PNP ligand) and [(tBu-PNP)Ir(H)] (3) react with CO2 to give the dearomatized complex [(tBu-PNP)Ir(CO)] (4) and water. Mechanistic studies have identified an adduct in which CO2 is bound to the ligand and metal, [(tBu-PNP-COO)Ir(H)2] (5), and a di-CO2 iridacycle [(tBu-PNP)Ir(H)(C2O4-C,O)] (6). DFT calculations confirm the formation of 5 and 6 as reversibly formed side products, and suggest an 1-CO2 intermediate leading to the thermodynamic product 4. The calculations support a metal-ligand-cooperation pathway in which an internal deprotonation of the benzylic position by the η1-CO2 ligand leads to a carboxylate intermediate, which further reacts with the hydride ligand to give complex 4 and water.

Original languageEnglish
Pages (from-to)6445-6454
Number of pages10
JournalJournal of the American Chemical Society
Issue number20
Publication statusPublished - May 25 2016

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

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