title: Synthesis and spectral characterization of ternary mixed-vanadyl β-diketonate complexes with Schiff bases.
abstract: A new method to synthesize some mononuclear ternary oxovanadium(IV) complexes of the general formula [VO(β-dike)(SB)] (where Hβ-dike=acetylacetone; benzoylacetone or dibenzoylmethane, HSB=Schiff bases) has been explored by stepwise substitutions of acetylacetonate ion of VO(acac)(2) with Schiff bases. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. The complexes were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, (1)H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of β-diketones and Schiff base anions in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with (51)V nucleus (I=7/2). Cyclic voltammograms of all the complexes displayed two-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Transmission electron microscopy (TEM) indicated spherical particles of ∼200 nm diameter. The synthesized complexes are mixed-ligand complexes showing a considerable hydrolytic stability in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes.
authors.affiliation: Coordination Chemistry Research Laboratory, Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273 009, India. drbpbaranwal@gmail.com
authors.forename: Balram Prasad
authors.initials: BP
authors.lastname: Baranwal
authors.forename: Kiran
authors.initials: K
authors.lastname: Tripathi
authors.forename: Alok Kumar
authors.initials: AK
authors.lastname: Singh
authors.forename: Saurabh
authors.initials: S
authors.lastname: Tripathi
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D007659:Ketones / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D012545:Schiff Bases / Q000138:chemical synthesis / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D014638:Vanadates / Q000138:chemical synthesis / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D007659:Ketones; D008024:Ligands; D012545:Schiff Bases; C075743:oxovanadium IV; D014638:Vanadates