Ternary complexes in solution: complex formation between the 1 : 1 thorium(IV)-alizarin maroon complex and thiosalicylic acid

Abstract

The stability constant of the ternary Th(IV) complex containing alizarin maroon (AZM) and as a second ligand thiosalicylic acid (TSA) in a 1 : 1 : 1 molar ratio was determined potentiometrically in 40%V/V ethanol-water medium (l= 0.1 M NaClO4; 25 ± 0.1 °C). Under identical conditions the binary complexes of thorium with both reagents have also been examined. For the equilibrium Th(AZM)2+ Th(TSA)2⇌ 2 Th(AZM)(TSA), the corresponding constant was log X= 3.6(0.75). The constant given in parentheses is due to ΔlogKTh= logKTh(AZM)Th(AZM)(TSA)– logKThTh(AZM).