Chelated iridium (III) bis-carbene complexes as air-stable catalysts for transfer hydrogenation
The new air-stable and moisture-insensitive Ir catalysts for efficient transfer hydrogenation of ketones contain a chelating bis(N-heterocyclic carbene) ligand. Most other hydrogen transfer catalysts show activity Rh > Ir, but we find Ir > Rh for these cases. Tuning of the ligand wingtip substituents, R, can greatly increase catalyst activity (R = neopentyl) or selectivity (R = isopropyl). Reactivity studies and isotopic labeling are consistent with a monohydride mechanism for the hydrogen transfer.
Albrecht, Martin; Miecznikowski, John R.; Samuel, Amanda; Faller, Jack W.; and Crabtree, Robert H., "Chelated iridium (III) bis-carbene complexes as air-stable catalysts for transfer hydrogenation" (2002). Chemistry & Biochemistry Faculty Publications. 38.
Albrecht, M.; Miecznikowski, J.R.; Samuel, A.; Faller, J.W.; Crabtree, R.H. “Chelated iridium (III) bis-carbene complexes as air-stable catalysts for transfer hydrogenation.” Organometallics, 2002, 21 (17), 3596-3604. doi:10.1021/om020338x.