Catalytic hydrogen transfer activity of cationic iridium(I) complexes containing α-diimines

Bikrani, Mohammed; Fidalgo, Luz; Garralda, María A.; Ubide, Carlos

doi:10.1016/s1381-1169(96)00372-x

Cited by 5 publications

(1 citation statement)

References 29 publications

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“…The in situ formed diazabutadiene complexes displayed moderate catalytic activity (entries 4−7), in particular with the better electron donor and less bulky cyclohexyl and adamantyl substituents. Their catalytic ability was, however, a little disappointing compared to the high activity reported for some similar Ir(I) systems possessing chelating bidentate N-donor ligands. 8o, Surprisingly, given its well-documented thermal instability, Crabtree's catalyst was reasonably active in transfer hydrogenation under these conditions (entry 13). Removal of volatiles from the reaction mixture in this case afforded a yellow-brown oily material which displayed resonances in the hydride region of the 1 H NMR spectrum, consistent with formation of a bis(phosphine) metal hydride complex.…”

Section: Resultsmentioning

confidence: 99%

Cationic Iridium Complexes Bearing Imidazol-2-ylidene Ligands as Transfer Hydrogenation Catalysts

et al. 2001

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The synthesis and characterization by X-ray crystallography of the complexes [Ir(cod)-(py)(L)]PF 6 (L ) IMes, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (2); L ) IPr, 1,3bis(2,6-diisopropylphenyl)imidazol-2-ylidene (3); L ) ICy, 1,3-bis(cyclohexyl)imidazol-2ylidene ( 4)) are reported. Complexes 2-4 have been employed as catalysts for transfer hydrogenation reactions from 2-propanol to a number of unsaturated substrates and their activity compared with that of the related cationic iridium(I) species [Ir(cod)(py)(SIMes)]-PF 6 (1), [Ir(cod)(py)(PCy 3 )]PF 6 (5), and complexes formed in situ from [Ir(cod)(py) 2 ]PF 6 and diazabutadienes (RNdCHCHdNR, DAB-R; R ) cyclohexyl, DAB-Cy; R ) 2,4,6-trimethylphenyl, DAB-Mes; R ) adamantyl, DAB-Ad; R ) 2,4,6-trimethoxyphenyl, DAB-trimethoxyphenyl). All complexes tested were found to be active catalysts for transfer hydrogenation of ketones, with complex 4 displaying the highest activity. Complex 4 also exhibits moderate activity toward simple olefins and an aromatic nitro compound.

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Section: Resultsmentioning

confidence: 99%