Ruthenium(II) complex catalysts bearing a 2,6-bis(tetrazolyl)pyridine ligand for the transfer hydrogenation of ketones

Three ruthenium(II) complex catalysts bearing 2,6-bis(tetrazolyl)pyridine were synthesized and applied in the transfer hydrogenation of ketones. Their different catalytic activities were attributed to the phosphine ligands in the 4-chloro-2,6-bis(1-(p-tolyl)-1H- tetrazol-5-yl)pyridine ruthenium(II) complexes. The ruthenium(II) complex based on 1,4-bis(diphenylphosphino)butane exhibited better catalytic activity, reducing a variety of ketones to their corresponding alcohols with >95% conversion.