Triruthenium carbonyl complexes containing bidentate pyridine–alkoxide ligands for highly efficient oxidation of primary and secondary alcohols

Abstract

Reactions of substituted pyridylalkanol 6‐CH3PyCH2CH(OH)R (R = Ph (L1H), R = 4‐CH3C6H4 (L2H), R = 4‐OCH3C6H4 (L3H), R = 4‐ClC6H4 (L4H), R = 4‐BrC6H4 (L5H), R = 4‐CF3C6H4 (L6H)) with Ru3(CO)12 in refluxing tetrahydrofuran afforded the corresponding ruthenium carbonyl complexes [6‐CH3PyCH2CHRO]2Ru3(CO)8 (R = Ph (1a), R = 4‐CH3C6H4 (1b), R = 4‐OCH3C6H4 (1c), R = 4‐ClC6H4 (1d), R = 4‐BrC6H4 (1e), R = 4‐CF3C6H4 (1f)) in good yields. These ruthenium complexes were well characterized using elemental analysis and Fourier transform infrared and NMR spectroscopies. Furthermore, their crystal structures were determined using single‐crystal X‐ray diffraction analysis. Complexes 1a–1f were found to be highly active toward oxidation of a wide range of primary and secondary alcohols to corresponding aldehydes and ketones within 5 minutes in the presence of N‐methylmorpholine‐N‐oxide as oxidant.