Scandium(III) and Yttrium(III) Complexes of Hydroxysalicylic Acid Ligands

Abstract

Interactions of scandium(III) and yttrium(III) with 2,X-dihydroxybenzoic acids (2,X-DHBA, X = 4-6) (H₃L) have been investigated in aqueous solution by potentiometric method at 25°C and at an ionic strength of 0.1 M (KNO₃ for Sc(III) and NaClO₄ for Y(III)). It has been observed that at low pH, the coordination of 2,X-DHBA ligands to Sc(III) occurs through salicylate sites; while Y(III) binds it only from carboxylate. In more basic media the hydrolytic equilibria lake place, either in 1 : 1 or in 1 : 2 mole ratios of Sc(III) or Y(III) : H₃L systems. The stability constants of the formed Sc(LH)⁺, Sc(LH)(H₂L), Y(H₂L)²⁺, Y(H₂L)₂⁺ type complexes and their mono hydroxo complexes have been determined.