Composition and geometry of oxovanadium(IV) and (V)-aminoethanol-Schiff base complexes and stability of their peroxo complexes in solution

Vanadium(IV) and (V) complexes (VO(sal-ae)) with Schiff bases prepared from 2-aminoethanol and salicylaldehyde and its derivatives have been synthesized and characterized in solid and in solution by EPR, IR, and UV-Vis spectroscopy. The complexes of both V(IV) and V(V) contain bridges (V-O-V) by alkoxy oxygens(oxo) in the solid state. The complexes of V(IV) in dichloromethane are binuclear,in which two alkoxy oxygens serve as bridges between the two metal atoms. They are mononuclear with one solvent ligated in the equatorial plane in each complex in dimethyl sulfoxide and methanol. The extent of the formation and the stability of organic hydroperoxide complexes of V(V) prepared from the V(IV)-Schiff base complexes increase with decreasing donor number of the solvent. The difference in electron-donating and withdrawing ability of the substituent groups affects the A values for the V(IV)-Schiff base complexes in DMSO. (C) 2003 Elsevier B.V. All rights reserved.