Study of stability constants of some of the transition metal complexes with β-diketones by spectrophotometery

In this study, the complexes of acetyl acetone(acac) with Cu(II), Cr(III) and Fe(III) cations were synthesized and their visible spectrum were recorded. The maximum wavelength of absorption was derived from the recorded spectrum. Using from procedure of continues variations (Job method) in maximum wavelength, optimized pH was formed; the complex and stoichiometry were defined. The stability constants of these complexes were determined by UV-Vis spectrometry. The other derivatives of acetylacetone such as benzoylacetone (Bac) and benzoyltrifluoroacetone (Btfac) were also determined. On the other hand, further study about the systems of water and water-ethanol 50 % and water-dioxane 75 % solution were also performed. The results show that benzoylacetone complexes are more stable than the benzoyltrifluoroacetone complexes. For the mentioned complexes, the arrangement of the solvent systems were as follow: water < water-dioxane 75 % < water-ethanol 50 %.