Metal-ligand cooperation in C-H and H2 activation by an electron-rich PNP Ir(I) system

Facile ligand dearomatization-aromatization as key steps

Eyal Ben-Ari, Gregory Leitus, Linda J W Shimon, David Milstein

Research output: Contribution to journalArticle

179 Citations (Scopus)

Abstract

Unusual reactions are reported, in which the aromatic PNP ligand (PNP = 2,6-bis-(di-tert-butylphosphinomethyl)pyridine) acts in concert with the metal in the activation of H2 and benzene, via facile aromatization/dearomatization processes of the ligand. A new, dearomatized electron-rich (PNP*)Ir(I) complex 2 (PNP* = deprotonated PNP) activates benzene to form the aromatic (PNP)Ir(I)Ph 4, which upon treatment with CO undergoes a surprising oxidation process to form (PNP*)Ir(III)(H)CO 6, involving proton migration from the ligand "arm" to the metal, with concomitant dearomatization. 4 undergoes stereoselective activation of H2 to exclusively form the trans-dihydride 7, rather than the expected cis-dihydride complex. Our evidence, including D-labeling, suggests the possibility that the Ir(I)-Ph complex is transformed to the dearomatized Ir(III)(Ph)(H) (independently prepared at low temperature), which may be the actual intermediate undergoing H2 activation.

Original languageEnglish
Pages (from-to)15390-15391
Number of pages2
JournalJournal of the American Chemical Society
Volume128
Issue number48
DOIs
Publication statusPublished - Dec 6 2006

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Aromatization
Metals
Chemical activation
Ligands
Electrons
Carbon Monoxide
Benzene
Pyridine
Labeling
Protons
Oxidation
Hydrogen
Temperature

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Metal-ligand cooperation in C-H and H2 activation by an electron-rich PNP Ir(I) system : Facile ligand dearomatization-aromatization as key steps. / Ben-Ari, Eyal; Leitus, Gregory; Shimon, Linda J W; Milstein, David.

In: Journal of the American Chemical Society, Vol. 128, No. 48, 06.12.2006, p. 15390-15391.

Research output: Contribution to journalArticle

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