Study of the stoichiometry of iron and vanadium nitrobenzohydroxamate complexes
Ehsan AA, Elmugdad AA, Dalia MO
Nitrobenzohydroxamic acid was synthesized by coupling methyl nitrobenzoate with free hydroxylamine hydrochloride. The compound was recrystallized in water/acetic acid mixture and identified by m.p(211-213C0), iron and vanadium color test and infrared spectra [showing absorption bands 3112 cm-1 (-- OH), 1691 cm-1 for( C=O) and 933 cm-1 for (N-O). Iron, and vanadium nitrobenzohydroxamate complexes were prepared by reacting nitrobenzohydroxamic acid with the corresponding metal salt in aqueous media at pH=3and pH=5 for Fe3+, V5+ complexes respectively. They show absorbance at a wavelength of maximum (λmax) 420nm, 520 nm for Fe3+ (red), V5+ (dark blue) complexes respectively indicating that the metal ligand complexes were formed from both. Showing the characteristic colors. Their purity of complexes was tested by their linear relationship of concentration and absorbance. Stoichiometry of iron and vanadium with the ligand is more level at different pH values. The results show 1:1, 1:2, for iron and 1:1, 1:2 for vanadium.