(i) The extraction and purification of the valuable metals by hydrometallurgical processes palladium : trans`[Pd(NH_(3))_(2)Cl_(2)], ` platinum : `[PtCl_(6)]^(2-)` gold : `[Au(CN)_(2)]^(-)` and `[AnCl_(4)]^(-)`, uransium :`[UO_(2)(SO_(4))_(3)]^(4-)`, cobalt: `[Co(D_(2)EHPA)_(2)]`. The neutral cobalt `D_(2)` EHPA complex is unique in its being soluble in kerosene , a property that makes possible the industrial solvent extration process.
(ii) Application of the coordination compound in the analytical chemistry covers both the aspects that is quantitative and qualitative.
for example addition of thiocyanate ion to the solution containing `Fe^(3+)` ions give rise a red colour to the thiocyanide complex. `[Fe(OH)_(5)(SCN)]^(2+)` ion concentration by constructing a calibration curve from a solution of the known concentration of `Fe^(3+)` concentration .
