Applications of coordination compounds

Question 1

Application of coordination compounds in analytical chemistry

Answer 1

• Coordination compounds find use in many qualitative and
  quantitative chemical analysis. The familiar colour reactions given
  by metal ions with a number of ligands (especially chelating ligands), as a result of formation of coordination entities, form the basis for their detection and estimation by classical and instrumental methods of analysis. Examples of such reagents include EDTA, DMG (dimethylglyoxime), –nitroso––naphthol, cupron, etc.
• Hardness of water is estimated by simple titration with Na2
  EDTA. The Ca2+ and Mg2+ ions form stable complexes with EDTA. The selective estimation of these ions can be done due to difference in
  the stability constants of calcium and magnesium complexes.

Question 2

Application of coordination compounds in metallurgy.

Answer 2

• Some important extraction processes of metals, like those of silver and gold, make use of complex formation. Gold, for example, combines with cyanide in the presence of oxygen and water to form the coordination
  entity [Au(CN)2]– in aqueous solution. Gold can be separated in metallic form from this solution by the addition of zinc.
• Similarly, purification of metals can be achieved through formation and subsequent decomposition of their coordination compounds. For example, impure nickel is converted to [Ni(CO)4], which is
  decomposed to yield pure nickel.

Question 3

Application of coordination compounds in biological systems

Answer 3

• The pigment responsible for photosynthesis, chlorophyll,
  is a coordination compound of magnesium.
• Haemoglobin, the red
  pigment of blood which acts as oxygen carrier is a coordination
  compound of iron.
• Vitamin B12
  , cyanocobalamine, the anti
  pernicious anaemia factor, is a coordination compound of cobalt.
• coordinated metal ions are the enzymes like, carboxypeptidase A
  and carbonic anhydrase act like catalysts of biological systems.

Question 4

Application of coordination compounds in industry.

Answer 4

• rhodium complex,
  [(Ph3P)3RhCl], a
  Wilkinson catalyst, is used for the hydrogenation of alkenes.
• Articles can be electroplated with silver and gold much more
  smoothly and evenly from solutions of the complexes, [Ag(CN)2] and [Au(CN)2]– than from a solution of simple metal ions.
• EDTA is used in text tile industry.

Question 5

Application of coordination compounds in black and white photography

Answer 5

In black and white photography, the developed film is fixed by
washing with hypo solution which dissolves the undecomposed
AgBr to form a complex ion, [Ag(S2O3)2]3–.

Question 6

Application of coordination compounds in medicinal field.

Answer 6

• Treatment of problems caused by the presence of metals in toxic proportions in plants or animal systems thus excess of copper and ion are removed by chelating ligands, D-penicillamine and desferrioxime B via the formation of coordination compounds.
• EDTA is used in the treatment of lead poisoning.
• Some coordination compounds of platinum effectively inhibit the growth of tumors like cisplatin