Dehydrogenation of Primary Alcohols via Radical Pathway by NNO Pincer‐Derived Manganese Complexes

ABSTRACT A family of tetranuclear‐manganese complexes ( Mn‐C1 – Mn‐C6 ) supported by 2‐(pyridin‐2‐yl)hydrazineylidene‐based tridentate NNO ligands has been synthesized and fully characterized by single‐crystal x‐ray diffraction, UV–vis, EPR, and HRMS analysis. The complexes feature μ ‐chlorido‐bridged Mn(II) centers and exhibit high thermal stability up to 250°C. In the presence of 30% aqueous H 2 O 2 , these catalysts promote the selective oxidation of primary benzylic and aliphatic alcohols to the corresponding aldehydes in excellent yields, displaying good functional‐group tolerance and a marked preference for primary over secondary substrates. Radical quenching experiments (TEMPO/BHT), together with spectroscopic studies, support a mechanism involving Mn–hydroperoxo species and a free radical/proton‐coupled electron transfer pathway. These results highlight structurally simple Mn–NNO platforms as promising, earth‐abundant catalysts for sustainable primary alcohol oxidation chemistry.