Mixed Picolinate and Quinaldinate Iron(III) Complexes for the Catalytic Oxidation of Alcohols with Hydrogen Peroxide

A series of Fe mixed picolinate and quinaldinate complexes that catalyze the H2O2 oxidation of alcohols are presented. The Fe catalysts are generated in situ by simple mixing of iron acetate with 6-methylpicolinic acid (6-MepicH) and 4-chloropicolinic acid (4-ClpicH); they showed high catalytic activity for H2O2 oxidation of 1-phenylethanol to acetophenone. Fe complexes generated in situ as precatalysts were successfully isolated and structurally characterized. Based on the single-crystal X-ray analysis and electrochemical measurements of the Fe complexes, the lability of picolinate and/or quinaldinate ligand and the redox potential of FeIII were found to be important factors for the catalytic reaction.