EPR and Spectroscopic Studies of Bis(S-methyl-3-isopropylidenehydrazinecarbodithioato)- 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, bis(S-methyl-3-isopropylidenehydrazinecarbodithioato)oxovanadium(IV), are described. The magnetic moment of 1.75 μ_B at room temperature is close to the spin only magnetic moment (1.73 μ_B). The experimental values of g_∥ = 1.960 and g_⊥ = 1.988 and the normal occurence of v(V=0) vibration suggest a monomeric five-coordinate square pyramical structure of the complex. A correlation was found between g_∥ and A_∥ 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 useful in characterizing aqueous pyridine cuts of asphaltenes with molecular weights less than 400 found in some heavy crude oils.