N-heterocyclic carbenes of iridium(I): ligand effects on the catalytic activity in transfer hydrogenation.

Chiral iridium(I) bis(NHC) complexes as catalysts for asymmetric transfer hydrogenation

The common use of NHC complexes in transition-metal mediated C–C coupling and metathesis reactions in recent decades has established N-heterocyclic carbenes as a new class of ligand for catalysis. The field of asymmetric catalysis with complexes bearing NHC-containing chiral ligands is dominated by mixed carbene/oxazoline or carbene/phosphane chelating ligands. In contrast, applications of comp...

Iridium(I) Complexes with Hemilabile N-Heterocyclic Carbenes: Efficient and Versatile Transfer Hydrogenation Catalysts

Electronically tunable N-heterocyclic carbene ligands: 1,3-diaryl vs. 4,5-diaryl substitution.

The catalytic activity of iridium-mediated transfer hydrogenation is readily tuned by electronic variation of the ligated tetraaryl-N-heterocyclic carbene and the installation of electron donating groups on the N-aryl substituents is more important than on the C-aryl substituents for effecting catalytic enhancement.

Highly enantioselective hydrogenation and transfer hydrogenation of cycloalkyl and heterocyclic ketones catalysed by an iridium complex of a tridentate phosphine-diamine ligand.

Ir complexes of chiral phosphine-diamine ligands catalyse the hydrogenation and transfer hydrogenation of aryl-piperidin-4-yl methanones, and ketones bearing both an aryl group and secondary alkyl substituent with up to 98% e.e., and with substrate to catalyst ratios of up to 4000.

Rhodium(III) Complexes Containing C4-Bound N-Heterocyclic Carbenes: Synthesis, Coordination Chemistry, and Catalytic Activity in Transfer Hydrogenation

Direct metalation of C2-protected diimidozolium salts with RhCl3 or [RhCl(cod)]2 and KI afforded a series of new rhodium(III) complexes with abnormally C4-bound, cis-chelating NHC ligands. The complexes were isolated as dimetallic species containing two (μ-I)3-bridged rhodium(III) centers. In the presence of coordinating ligands such as CH3CN, PPh3, or dppe, the dimeric structure is readily cle...