Coordination compounds of chromium(III) with different complexones and citric acid in aqueous solutions

A spectrophotometric study of heteroligand chromium(III) complexes with iminodiacetic (H2Ida), N-methyliminodiacetic (H2Mida), N-(β-hydroxyethyl)iminodiacetic (H2Heida), nitrilotriacetic (H3Nta), ethylenediaminetetraacetic (H4Edta), and citric acids (H4Cit) showed that complexation in ternary systems depends on the concentrations of the reagents and the pH of the medium. The resulting complexes were [Cr(HIda)(H2Cit)], [Cr(HMida)(H2Cit)], [Cr(HHeida)(H2Cit)], [Cr(HHeida)(HCit)]−, [Cr(HNta)(H2Cit)]−, [Cr(HNta)(HCit)]2−, [Cr(Nta)(HCit)]3−, [Cr(HEdta)(HCit)]3−, and [Cr(Edta)(HCit)]4−. The logarithms of their stability constants are 41.97 ± 0.47, 43.54 ± 0.62, 42.32 ± 0.62, 36.34 ± 0.26, 43.70 ± 0.25, 39.75 ± 0.45, 32.93 ± 1.56, 46.46 ± 0.80, and 41.71 ± 0.81 , respectively (I = 0.1 (NaClO 4)).