Abstract

This work reports the synthesis and characterization of ruthenium(II) complexes containing nitrogen-phosphorus-nitrogen (NPN) ligands, with L1 = N-(phenyl(pyridin-2-ylamino)phosphino)pyridin-2-amine and L2 = 4-methyl-N-((4-methylpyridin-2-ylamino)(phenyl)phosphino)pyridin-2-amine. The ruthenium complexes RuCl2PPh3(L1) (1) and RuCl2PPh3(L2) (2) show high activities in catalytic transfer hydrogenation of different substituted benzylideneanilines, with turnover frequencies up to 5882 h?1 and 5294 h?1, respectively. The RuCl(CO)PPh3(L1) (3) and RuCl(CO)PPh3(L2) (4) complexes were non-active in the reaction studied. Theoretical calculations conducted for complex 4 showed that the carbonyl group promotes ?-orbital interactions and backdonation phenomena from the metal centre to the ?* orbitals in the CO ligand, presenting a strong orbital contribution. This supports the hypothesis that complexes 3 and 4 are less reactive species and therefore present poor or null catalytic performance in the reaction studied. © 2024