Metal chelates of some Schiff bases derived from diamines and 2-hydroxyacetylacetophenone with Cr 3+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , and Cd 2+ of stoichiometric ratios 1:1 and 2:1 (M:L) have been synthesized and characterized by different spectrophotometric techniques. It is found that the coordination site of ligands differs depending on the kind of metal ions. Thus, Cr 3+ , Fe 3+ , and Co 2+ enter in the outer O 2 O 2 compartment, whereas Ni 2+ , Cu 2+ , and Cd 2+ enter into N 2 O 2 site. The g-values of Cu 2+ complexes suggest square-planar geometry; this is confirmed from the ESR spectra of its complexes.

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Simple, rapid, accurate, precise and sensitive spectrophotometric method for the microdetermination of enalapril maleate (ENM) and lisinopril dihydrate (LIS) has been developed. The method is based on oxidation of the drug by potassium permanganate in acidic medium and determine the unreacted oxidant by measuring the decrease in absorbance for three different acidic dyes; acid red 73 (AR), amaranth dye [acid red 27] (AM) and acid orange 7 (AO) at a suitable λ max (510, 521 and 484 nm for ENM and 509, 521 and 485 nm for LIS), respectively. Regression analysis of Beer's law plots showed good correlation in the concentration ranges 0.7-12, 0.5-7.6 and 0.6-9.5 µg mL -1 and 0.5-9.0, 0.4-6.1 and 0.4-7.2 µg mL -1 for ENM and LIS using AR, AM and AO, respectively. The apparent molar absorptivity, Sandell sensitivity, detection and quantitation limits are calculated. Statistical treatment of the results reflects that the proposed procedures are precise, accurate and easily applicable for the determination of ENM and LIS in pure and in pharmaceutical preparations.