Rhodium(III) NCN pincer complexes catalyzed transfer hydrogenation of ketones

Air-stable monomeric rhodium(III) NCN pincer complexes were synthesized via direct C–H bond activation of 1,3-bis(2-pyridyloxy)benzene, 3,5-bis(2-pyridyloxy)toluene and 3,5-bis(2-pyridyloxy)anisole with RhCl3·3H2O in ethanol under reflux. The synthesized complexes were characterized by elemental analysis and 1H NMR. One of the complexes was structurally characterized by X-ray analysis. An investigation into the catalytic activity of the complex 1a as catalyst for transfer hydrogenation of ketones to alcohols at 82 °C in the presence of iPrOH/KOH was undertaken with the conversions up to 99%.

Graphical abstractAir-stable monomeric rhodium(III) NCN pincer complexes were synthesized via direct C–H bond activation of 1,3-bis(2-pyridyloxy)benzene, 3,5-bis(2-pyridyloxy)toluene and 3,5-bis(2-pyridyloxy)anisole with RhCl3·3H2O in ethanol under reflux. The synthesized complexes were characterized by elemental analysis and 1H NMR. One of the complexes was structurally characterized by X-ray analysis. An investigation into the catalytic activity of the complex 1a as catalyst for transfer hydrogenation of ketones to alcohols at 82 °C in the presence of iPrOH/KOH was undertaken with the conversions up to 99%.Figure optionsDownload full-size imageDownload as PowerPoint slide