Spectrophotometric determination of ruthenium(III) with 5,7-dichloro-, 5,7-dibromo-and 5,7-dinitro-8-hydroxyquinoline n-oxide

The deeply coloured 1:1 and 1:2 (metal : ligand) complexes of ruthenium(III) with 5,7-dichloro-8-hydroxyquinoline N-oxide (II), 5,7-dibromo-8-hydroxyquinoline N-oxide (III) and 5,7-dinitro-8-hydroxyquinoline N-oxide (IV) have been investigated spectrophotometrically in 60% acetone medium, and are suggested for the spectrophotometric determination of ruthenium(III) in presence of other platinum metals. The stability constants (log β1 and log β2 (determined spectrophotometrically) decrease in the order III < II < IV, which is the same as that of the basicity of the ligands.