2,6-Bis(3,5-dimethylpyrazol-1-yl)pyridine: A Useful Pseudo-N₃ Ligand in Efficient Ruthenium(II)-Catalyzed Transfer Hydrogenation of Ketones

Transfer hydrogenation of ketones was efficiently carried out with a ruthenium(II) complex bearing the ligand 2,6-bis(3,5-dimethylpyrazol-1-yl)pyridine (Me4BPPy), i.e., RuCl2(PPh3)(Me4BPPy), in 2-propanol at 82 °C. The single-crystal structure of the complex was first characterized by an X-ray crystallographic study, correcting the mistaken structural assignment of the complex in the literature. The results have demonstrated that the new family of ligands of the type Me4BPPy can act as pseudo-N3 ligands to construct transition-metal catalysts.