Mixed‐Valence Vanadium (IV/V) Glycolates and Lactates with N‐Heterocycle Ligands: Localized Structures and Catalytic Oxidation of Thioanisole

Abstract

Dimeric mixed‐valence vanadium (IV/V) glycolates and lactates with N‐heterocycle ligands, [V2O3(phen)3(glyc)]Cl·7H2O (1), [V2O3(phen)3(S‐lact)]Cl·5.5H2O (2), (NH4)2[V2O3(bpy)2(glyc)2]Cl·4H2O (3), (NH4)[V2O3(bpy)2(S‐lact)2]·7H2O (4) and (NH4)2[V2O3(bpy)2(R,S‐lact)2]Cl·H2O (5), have been isolated in a wide pH range from weak acidic to alkaline solutions (H2glyc = glycolic acid, H2lact = lactic acid, phen = 1,10‐phenanthroline, bpy = 2,2′‐bipyridine). The glycolates and lactates in 1 and 2 chelate to VV whereas in 3–5 chelate to VIV and VV with α‐alkoxy and α‐carboxy groups. These complexes feature interesting localized O=VIV–O–VV=O bridging structures, which are supported by structural analyses, bond valance calculations, UV/Vis, EPR experiments and exhibit different electrochemical behaviors. These complexes were further used for the selective oxidation of thioanisole to methyl phenyl sulfoxide.