Iron(III) Chelates of substituted 8‐hydroxy quinoline‐7‐sulfonic acids some physico chemical properties and analytical applications

Abstract Iron(III) forms in acidic aqueous medium green coloured complexes with 8‐hydroxy quinoline‐7‐sulfonic acid (RI), 5‐chloro‐8‐hydroxy quinoline‐7‐sulfonic acid (RII), 5‐bromo‐8‐hydroxy quinoline‐7‐sulfonic acid (RIII) and 5‐iodo‐8‐hydroxy quinoline‐7‐sulfonic acid (RIV). The composition of the complexes was studied by three different methods spectrophotometrically and the complexes were found to have the general formulae Fe(III)‐ R (where R stands for the ligand). The stability constants of the complexes, the free energy of formation, entropy and enthalpy changes and some analytical applications have been reported.