Importance of Coordination Compounds Preparation and Properties
Importance of Coordination Compounds :
The complexes have great importance in various fields. Some of importances of complexes are given below:
→ In analytical chemistry : Coordination compounds find their applications in both qualitative and quatitative method of analysis:
→ The separation of Ag+ from Hg22+ in the first group of analysis is based on the fact that silver chloride is soluble in aqueous ammonia and Hg2 Cl2 forms a black insoluble material.
→ The separation of II B group sulphides from II A sulphides is based on the fact that sulphides of IIB group form complex sulphides with yellow ammonium sulphide which are soluble while sulphides of IIA group do not react.
→ The detection of Cu+2 is based on complex formation
→ Fe+3 is detected by formation of a blood red coloured complex with KSCN.
→ The detection and estimation of Ni+2 is based on the formation of a red complex with dimethyl glyoxime.
→ The detection of copper in the presence of cadmium in the second group of chemical analysis can be made by cyanide complexes.
→ The copper complex is more stable than the cadmium complex and therefore, when H2S gas is passed through a mixture of these complexes only Cd+2 gets precipitated as CdS leaving a blue coloured solution of copper complex.
→ Nessler’s reagent forms a brown complex (NH4)2 [HgI4] with ammonium ions. This reaction is used for detection of ammonium ion.
→ EDTA is used as complexing agent in volumetric analysis of metal ions like Ca+2, Mg+2 etc. so by using EDTA, hardness of water can be estimated.
→ In electroplating : Metal complexes release metal slowly and thus give a uniform coating in electroplating of the metal on the desire object. Cyano complexes of silver, gold, copper etc. are used for the electrodeposition of these metals.
→ In photography : In photography, the image on the negative is fixed y dissolving all the remaining silver halides with hypo solution in the form of a soluble complex.
→ In biological processes : Coordination compounds play many important roles in animals and plants.
- Chlorophyll : a complex of Mg2+
- Haemoglobin : a complex of Fe2+
- Vitamin B12 : a complex of Co2+
- Insulin : a complex of Zn+2
→ In medicinal field : The complex of calcium with EDTA is used for the treatment of lead poisoning. The platinum complex cis- [PtCl2(NH3)2] is known as cis-platin acts as an antitumor agent in the treatment of cancer.
→ In metallurgical process : Complex formation techniques are also used for the extraction of metals such as gold and silver from their ores. Silver or gold ores are treated with sodium cyanide solution with continuous passing of air through solution. Silver/gold dissolves as cyanide complex and pure silver is precipitated by the addition of zinc.
→ Purification of nickel (Mond’s Method) and purification of Ti. (Van-Arkel Method) are also based on complex formation.