LAUSR

Several new trinuclear ruthenium carbonyl complexes chelated with 6-bromopyridine alcohol ligands, [6-bromopyC(CH2)4O]Ru3(CO)9 (1a), [6-bromopyC(CH2)5O]Ru3(CO)9 (1b), [6-bromopyC(Me)2O]Ru3(CO)9 (1c) and [6-bromopyCMeC6H5O]Ru3(CO)9 (1d), were synthesized by the reaction of Ru3(CO)12 with 6-bromopyC(CH2)4OH (L1H), 6-bromopyC(CH2)5OH (L2H), 6-bromopyC(Me)2OH (L3H) and 6-bromopyCMeC6H5OH (L4H) in refluxing THF, respectively. The free ligands L1H–L4H were synthesized by the nucleophilic reaction of lithium salt (generated from 2,6-dibromopyridine and n-BuLi) with the corresponding ketones. Furthermore, these pyridine-based ligands were characterized by NMR spectroscopy and elemental analyses. All the four ruthenium carbonyl complexes were well characterized by NMR, IR, single-crystal X-ray crystallography, etc. Complexes 1a–1d were found to exhibit high catalytic activities for the dehydrogenative oxidation of secondary alcohols to give their corresponding products in good to excellent yields.