Rhodium-catalyzed transfer hydrogenation with functionalized bis(phosphino)amine ligands

A series of novel cationic mononuclear rhodium(I) complexes with the P–N–P ligands have been prepared starting from the complex [Rh(cod)2]BF4. The structural elucidation of the complexes was carried out by elemental analyses, IR and multinuclear NMR spectroscopic data. Furthermore, the complexes were applied to the transfer hydrogenation of ketones in the presence of 2-propanol as the hydrogen source. Catalytic studies showed that all complexes are excellent catalytic precursors for the transfer hydrogenation of aryl alkyl ketones in 0.1 M iso-PrOH solution. Especially, [Rh((Ph2P)2N-C6H4-4-CH(CH3)2)(cod)]BF4 acts as an excellent catalyst giving the corresponding alcohols in excellent conversion up to 99% (TOF ⩽ 1980 h−1).

Graphical abstractWe describe a series of novel cationic mononuclear rhodium(I) complexes with the P–N–P ligands have been prepared starting from the complex [Rh(cod)2]BF4. The structures of all new compounds have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy, elemental analysis. Furthermore, the complexes were applied to the transfer hydrogenation of various ketones in the presence of 2-propanol as the hydrogen source. Especially, [Rh((Ph2P)2N-C6H4-4-CH(CH3)2)(cod)]BF4 acts as an excellent catalyst giving the corresponding alcohols in excellent conversion up to 99% (TOF ⩽ 1980 h−1).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A series of novel Rh(I) complexes with the P–N–P ligands were synthesized. ► All complexes are excellent catalytic precursors for the transfer hydrogenation. ► Complex 8 acts as an excellent catalyst giving the alcohols (TOF ⩽ 1980 h−1).