The complex formation of iron(III) with 3-((2-hydroxyphenyl)diazenyl)pentadione-2,4 and diantipyrylmethane was investigated by spectrophotometric method and highly selective method of determination of its microamounts in natural objects established. It's found that at pH 2.0-2.5 in the presence of diantipyrylmethane Fe(III) forms with reagent intensively colored mixed-ligand complex Fe(III)-R-DAM with the ratio of components 1:2:1. During formation of mixed-ligand complex bathochromic shift and hyperchromic effect are observed compared to binary complex. The optimum conditions of formation of same and mixed-ligand complexes of Fe(III) were determined and the main spectrophotometric characteristics calculated. By spectrophotometric method stability constants of complexes are determined and found that mixed-ligand complex Fe(III)-R-DAM has high stability: lgβ(Fe-R)=5.76±0.10; lgβ(Fe-R-DAM)=14.65±0.26. The new highly selectivity spectrophotometric method for the determination of iron(III) has been developed and applied for the determination of its quantity in volcanic mountain rocks.

A new organic reagent based on benzoylacetone, 3-(4'-fluorophenylimine)-1-phenylbutanone-1 was synthesized and its crystal structure determined by X-ray structural analysis. Reagent crystals are monoclinic: a=6.4520(6) Ǻ, b=28.685(2) Ǻ, c=7.2003(6) Ǻ, α=90°, β=91.163(2)°, γ=90°, V=1332.3(2)Å 3 , space group P2 1 /n, Z=4. Results of X-ray diffraction analysis showed that the reagent molecule in the crystal has trans-configuration. The reagent dissociation constant (pK = 9.89 ± 0.05) and the stability constants of its complexes with some metals were determined by means of potentiometric titration.method The complexation of the reagent with iron (III) in the presence of dianthipirilmethane and its homologsdiantipyrylphenylmethane and diantipyryl-o-oxyphenylmethane was studied spectrophotometrically. A highly selective method for the direct determination of iron micro-quantities in red and Hovsani onions developed.

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