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, [V 2 O 3 (phen) 3 (glyc)]Cl · 7H 2 O ( 1 ), [V 2 O 3 (phen) 3 ( S ‐lact)]Cl · 5.5H 2 O ( 2 ), (NH 4 ) 2 [V 2 O 3 (bpy) 2 (glyc) 2 ]Cl · 4H 2 O ( 3 ), (NH 4 )[V 2 O 3 (bpy) 2 ( S ‐lact) 2 ] · 7H 2 O ( 4 ) and (NH 4 ) 2 [V 2 O 3 (bpy) 2 ( R , S ‐lact) 2 ]Cl · H 2 O ( 5 ), have been isolated in a wide pH range from weak acidic to alkaline solutions (H 2 glyc = glycolic acid, H 2 lact = lactic acid, phen = 1,10‐phenanthroline, bpy = 2,2′‐bipyridine). The glycolates and lactates in 1 and 2 chelate to V V whereas in 3 – 5 chelate to V IV and V V with α‐alkoxy and α‐carboxy groups. These complexes feature interesting localized O=V IV –O–V V =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.