Coordination Compounds: Application of Coordination Compounds (For CBSE, ICSE, IAS, NET, NRA 2022)

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Isomerism

Compounds which have the same molecular formula, but different structural formulae are said to be isomers.

The isomerism can be classified as:

The Isomerism

Structural Isomerism

This may be subdivided into subclasses as:

  • Ionization isomerism: When the compounds yield different ions in solution, e. g. and .
  • Hydration isomerism: These compounds show different conductivities in solution, and they precipitate different amounts of silver chloride from cold silver nitrate solution. e. g. (violet) , (light green) , and (dark green) .
  • Coordination isomerism: When cation and anion both are complexes. e. g. and .
  • Linkage Isomerism: Complexes in which linkages of ligand is different for example and .

Geometrical Isomerism

  • These are isomers in which the composition of the first coordination sphere is the same, but the geometrical arrangement of the ligands varies.
  • These are often called cis-trans isomerism referring to relative positions of two selected ligands.
  • The isomerism is only possible for coordination numbers greater than or equal to four.

For example,

Geometrical Isomerism

Optical Isomerism

  • Any molecule which contains no plane or center of symmetry may exist in two forms which are non-superimposable mirror images of one another is called optical isomers.
  • These have identical chemical and physical properties except that they rotate the plane of plane-polarized light equally but in opposite directions, and they react differently with other optically active compounds.

Application of Coordination Compounds

Extraction of Metals

Cyanide ions are used for the for the extraction of gold and silver.

The crushed ore is heated with an aq. cyanide solution in the presence of air to dissolve the gold by forming the soluble complex ion .

Medicines

EDTA is a chelating agent which is used in the treatment of lead poisoning.

Qualitative Analyses

Complex formation is useful for qualitative analyses.

  • ion forms complex on addition of ammonia .
  • forms a blue complex with , i.e.. .
  • Cobalt (II) gives colour with due to the formation of complex .
  • Nickel forms a red complex with dimethylglyoxime .
  • Separation of from and Soluble.
  • Separation of IIA and IIB groups.

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