Synthesis and characterization of oxovanadimn(IV) complexes incorporating novel tridentate OOO donor ligands

VOSO4 reacts with equivalent amount of 1-(2-hydroxyphenyl)butane-1,3-dione (H2L1) and 1-(2-hydroxyphenyl)-3-phenyl-propane-1,3-dione (H2L2) in presence of two equivalent sodium acetate in 50% (v/v) aqueous-methanolic medium to afford the brown complexes [(VO)-O-IV(L-1)(H2O)(n)], (1) and [(VO)-O-IV(L-2)(H2O)](n) (2) respectively. IR spectra and solubility of complexes in common organic solvent along with the geometry of the ligands indicated the polymeric nature of the complexes. Complexes are one-electron paramagnetic and are EPR active displaying axial EPR spectra in HMSO solution at 77 K. They exhibit three transitions in the visible region at similar to 660 nm, similar to 590 urn and similar to 430 nm d(xy) -> d(xz), d(yz); d(xy) -> d(x2-y2) and d(xy) -> d(z2) respectively.