Imine Hydrogenation by Tribenzylphosphine Rhodium and Iridium Complexes

The iridium complexes [Ir(PBz 3 ) 2 (COD)]PF 6 and [Ir(py)(PBz3)(COD)]PF6 are effective catalyst precursors for the homogeneous hydrogenation of N-(β-naphthylmethylene)aniline (NβNA) to naphthalene-2-ylmethylphenylamine (PBz 3 = tribenzylphosphine; COD = 1,5-cyclooctadiene; py = pyridine). For comparative purposes, other iridium and rhodium catalysts modified with either PBz 3 or PPh 3 have been tested as catalysts for NβNA hydrogenation. A kinetic study of this reaction catalyzed by [Ir(PBz 3 ) 2 -(COD)]PF 6 , [Ir(py)(PBz3)(COD)]PF6, and [Rh(PPh 3 ) 2 (COD)]PF 6 , together with in situ NMR experiments, has led us to propose catalytic cycles for the three precursors.