Synthesis and characterization of some oxovanadium(V) complexes with internally functionalized oximes: Crystal and molecular structures of heptacoordinated [VO{ONdouble bond; length as m-dashC(CH3)(C4H3O-2)}3] and [VO{ONdouble bond; length as m-dashC(CH3)

New oxovanadium(V) complexes with internally functionalized oximes of the type VO{OPri}3−n{ONdouble bond; length as m-dashC(CH3)(Ar)}n] (where Ar = C4H3O-2, C4H3S-2 and C5H4N-2 and n = 1–3) have been prepared in quantitative yields by the reaction of VO(OPri)3 with the corresponding oximes in various stoichiometric ratios in refluxing anhydrous benzene. The products have been characterized by elemental analyses and spectroscopic (FT IR, 1H, 13C{1H} and 51V NMR) studies. FAB mass spectral analysis of [VO{OPri}{ONdouble bond; length as m-dashC(CH3)C4H3S}2] indicates the monomeric nature of the complex. 51V NMR values for these complexes suggest the formation of tetra-coordinate species in solution. However, the single crystal X-ray diffraction studies of [VO{ONdouble bond; length as m-dashC(CH3)(C4H3O-2)}3] and [VO{ONdouble bond; length as m-dashC(CH3)(C4H3S-2)}3] · 0.5C6H6 exhibit the presence of vanadium(V) atoms in a unique hepta-coordination state with distorted pentagonal bipyramidal geometry in the solid state. The oxo- atom occupies the axial position while the oximato ligands are bonded in a dihapto (η2-N,O) manner with the formation of three membered rings.