Ternary complexes in solution: mixed-ligand complexes of thorium(IV) with alizarin maroon and secondary ligands containing oxygen or nitrogen as donor atoms

Abstract

The stability constants of the Th(lV) complexes containing Alizarin Maroon (AZM) and as a secondary ligand (L) salicylic acid (SA), 5-sulphosalicylic acid (SSA), 5-nitrosalicylic acid (NSA), 2,2'-bipyridyl (bipy) or 1,lO-phenanthroline (phen) were determined potentiometrically at 25 "C with an ionic strength (1) of 0.1 M (NaC104), and in a 20% WV aqueous ethanol medium.All of these mixed-ligand complexes are more stable than one would expect. The stability of the ternary complexes is discussed in relation to the natures of the secondary ligands involved. The solution spectrum of the complex is characterised by an absorption band with h, , , .at 580 nm within the pH range 4.6-5.5. The ternary system obeys Beer's law between 2.3 and 22.5 yg ml-1 of thorium with a molar absorptivity of 1.1 x 104 I mol-1 cm-1. Finally, a sensitive method has been developed for the micro-determination of thorium based on the formation of the Th -AZM -SSA ternary complex.

2‐Hydroxy‐1‐naphthaldehyde‐P‐hydroxybenzoichydrazone: A New Chromogenic Reagent for the Determination of Thorium(IV) and Uranium(VI)

“…A number of reagents have been used for the spectrophotometric determination of uranium and thorium. Among the various chromogenic agents reported for the determination of thorium (IV), most of them were found to be nonselective involving in serious interference from the diverse ions [6][7][8][9]. Majority of the reported methods require prior removal of closely associated metal ions and hence lack selectivity.…”