Importance of Coordination Compounds:
The coordination compounds constitute the minerals, plants, present in animals, used in the field of metallurgy, biochemistry, water softening, electrochemistry, textile dyeing, bacteriology, analytical chemistry etc. and so are of great importance. Some of the important applications of coordination complexes are as follows-
(1) In Analytical Chemistry-
(a) Fe3+ ions can be detected by means of red coloured sulphatocyanide complex.
|Fe3+ + SCN– ————> [Fe(SCN)]2+|
(b) Copper salts give blue colour with NH3 due to the formation of Tetrammine copper (II) complex.
|Cu2+ + 4NH3 ————> [Cu(NH3)4]2+ (Blue Colour)|
(c) Ni2+ ions are estimated as their red complex with Dimethyl glyoxime.
(2) In Photographic Processes- In photography, to fix the image on the negative, all the remaining silver salts are washed away from the film by washing it with a solution of sodium thiosulfate when soluble Na3[Ag(S2O3)2] complex is formed.
|AgX + 2Na2S2O3 ————> Na3[Ag(S2O3)2] (soluble) + NaX (soluble)|
(3) In Metallurgical Operations- Silver and gold are extracted from their respective ores by treatment with NaCN solution which involves complex formation.
|Ag+ (aq) + 2NaCN (aq) ————> Na[Ag(CN)2] (aq) + Na+|
Au+ (aq) + 2NaCN (aq) ————> Na[Au(CN)2] (aq) + Na+
(4) In Electroplating- Cyano complexes of Cu, Cd, Ag and Au are used for the electrodeposition of these metals.
(5) In Biological Process-
(a) The green colouring matter of plants called chlorophyll is a complex of Mg (II) which acts as a catalyst in the Photosynthesis of carbohydrates from CO2 and H2O.
|6CO2 + 6H2O —-Chlorophyll——–> C6H12O6 + 6O2|
(b) Vitamin B12 (cyanocobalamin) is a complex of Co (III) which acts as an enzyme in the formation of red blood cells and is very important for the treatment of Pernicious anaemia.
(c) Haemoglobin, the red pigment in the blood is a complex of Fe (II) which transports oxygen from the lungs to the various parts of the body.
(6) The complex Cis-[Pt(NH3)2Cl2] known as cisplatin is used as an antitumor agent in the treatment of cancer.