Organometallic compounds containing vanadium

Residua and heavy oils contain impurities other than sulfur, nitrogen, and oxygen, and the most troublesome of these impurities are the organometallic compounds of nickel and vanadium. The metal content of a residuum or heavy oil can vary from several parts per million (ppm) to more than 1000 parts per million (Table 6-15), and there does seem to be more than a chance relationship between the metals content of a feedstock and its physical properties (Reynolds, 1997 Speight, 1999). In the hydrodesulfurization of the heavier feedstocks the metals (nickel plus vanadium) are an important factor since large amounts (over 150 ppm) will cause rapid deterioration of the catalyst. The free metals, or the sulfides, deposit on the surface of the catalyst and within the pores of the catalyst, thereby... 

Complexes containing vanadium in low oxidation states, apart from organometallic compounds, are known with ligands such as bipy, phen, nitric oxide, and tertiary phosphines, which stabihze such oxidation states. Depending on their electronic structure, V and V complexes may be diamagnetic, which permits study by NMR spectroscopy, and EPR spectroscopy has been used to study paramagnetic V complexes. 

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