Structural characterization of pentadentate salen-type Schiff-base complexes of oxovanadium(IV) and their use in sulfide oxidation

Pentadentate Schiff-base complexes of oxovanadium(IV), the ligands of which were derived from salicylaldehyde derivatives with a variety of substituents and two kinds of amines (2,2′-bis(aminoethyl)amine and 3,3′-bis(aminopropyl)amine), were prepared, and their coordination geometries in the solid state were determined by X-ray diffraction and IR measurements and those in CH2Cl2 by EPR measurements. They were found to retain distorted octahedral coordination in the solid state. They showed the structural change depending on the type of the substituent. The complexes which reacted with tert-butylhydroperoxide converted methyl phenyl sulfide to the corresponding sulfoxide at lower rates of reaction than tridentate N-salicylidene-2-aminoethanolato oxovanadium(IV) ([VO(salae)]) and tetradentate (N,N′-bis(salicylidene)ethylenediaminato)oxovanadium(IV) ([VO(salen)]).