EPR AND SPECTROSCOPIC STUDIES OF ROPYLIDENEHYDRAZINECARBODITHIOATO)-OXOVANADIUM(IV) AS MODEL-COMPOUND FOR VANADIUM BOUND TO NITROGEN AND SULFUR HETEROATOMS

The synthesis and spectroscopic and EPR characterization of a vanadyl complex with acetone Schiff base, ropylidenehydrazinecarbodithioato)ox ovanadium(IV), are described. The magnetic moment of 1.75 mu(B) at roo m temperature is close to the spin only magnetic moment (1.73 mu(B)). The experimental values of g(parallel-to) = 1.960 and g(perpendicular- to) = 1.988 and the normal occurence of nu(V=O) vibration suggest a mo nomeric five-coordinate square pyramical structure of the complex. A c orrelation was found between g(parallel-to) and A(parallel-to) of the title compound when compared with other model compounds of the vanadyl complexes in which possible combinations of four ligands may include all nitrogen (N4) and all sulfur (S4). This information could be usefu l in characterizing aqueous pyridine cuts of asphaltenes with molecula r weights less than 400 found in some heavy crude oils.