Metal-ligand cooperation in C-H and H2 activation by an electron-rich PNP Ir(I) system: Facile ligand dearomatization-aromatization as key steps

Journal of the American Chemical Society

Volumn 128, Issue 48, 2006, Pages 15390-15391

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

^a WEIZMANN INSTITUTE OF SCIENCE   (Israel)

Author keywords

[No Author keywords available]

Indexed keywords

IRIDIUM; LIGAND; METAL;

AROMATIZATION; ARTICLE; CATALYSIS; CRYSTAL STRUCTURE; ISOMERIZATION; PHOSPHORUS NUCLEAR MAGNETIC RESONANCE; PROTON NUCLEAR MAGNETIC RESONANCE; X RAY CRYSTALLOGRAPHY;

EID: 33845323773     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja066411i     Document Type: Article

References (19)

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11. The protons were integrated with a time delay of 20 s, calibrated to the pyridinic aromatic protons.
12. 1H NMR spectrum: one characteristic signal at 5.67 ppm as a broad doublet and two multiplets at 6.45-6.85 ppm. The Ir-H appears at -47 ppm. For detailed assignments see Supporting Information.
13. Migration of the hydride ligand might be either intra- or intermolecular. Experimental and theoretical studies of the mechanism are in progress.
14. While CO coordination to Ir(I) followed by proton migration to the metal cannot be excluded at this stage, we think that it is less likely because of the lower electron density at the Ir(CO) center. The mechanism of this process is being studied.
15. Preliminary DFT calculations showed that the cis-isomer is more stable then the trans-isomer and should have been observed had it been formed.
16. (a) Rybtchinski, B.; Ben-David, Y.; Milstein, D. Organometallics 1997, 16, 3786.
17. (b) Li, S. H.; Hall, M. B. Organometallics 1999, 18, 5682.
18. However, no NMR evidence for an equilibrium involving 3 was obtained upon cooling solutions of 4 to -80°C.
19. 2 addition across an Ir(III)-amide bond was reported: Fryzuk, M. D.; Montgomery, C. D.; Rettig, S. J. Organometallics 1991, 10, 467.