Determination and comparison of the stability constants of some bivalent ion complexes of 5,7‐dichloro‐, 5,7‐dibromo‐, and 5,7‐dinitro‐8‐Hydroxyquinoline and their N‐oxides

The stability constants of complexes of Mn ++ , Fe ++ , Co ++ , Ni ++ , Cu ++ , Zn ++ , Cd ++ and UO   ++ 2with 5,7‐dichloro‐, 5,7‐dibromo‐ and 5,7‐dinitro‐8‐hydroxyquinoline and their corresponding N‐oxides have been determined in 75 + 25 v/v dioxan + water medium at 35°C in presence of 0.20 M sodium perchlorate by pH‐titration technique as given by I RVING and Rossotti. A possible explanation for the observed orders of the stability constants of the metal complex with the different ligands, and of the complexes of a particular ligand with different metal ions is also proposed.