Essay On Coordination Compounds

COORDINATION COMPOUNDS:

Coordination compounds are those which are electrically neutral and contain complex ions. Complex ions are those compounds in which central metal atom is bonded to ligand by coordinate covalent bond. The complex can be charged so coordination compound is balanced by counter ion.

Coordinate covalent bond is the bond in which electron pair is donated by one bonded atom only. The atoms which donate and accept the pair of electron are called donor and acceptor respectively. Ligand can be anion or neutral molecules. This contains a pair of electron to donate to metal atom or ion. These are also called Lewis base. Metal atom accepts the pair of electron from ligand and this is also called Lewis acid.

Coordination number: is the number of ligand or donor atom bonded to

Determination by spectrophotometer: coordination compounds which can absorb light can be determined by this method.

3. Precipitation of complexes: when compounds are extracted with organic solvents and can be easily separated from aqueous solution this process is used to identify them

EXTRACTION OF METALS

• These compounds are used in the extraction of metals. The metals can be gold, nickel, cobalt, silver and copper.

By using aqueous ammonia, nickel as ammine complex can be extracted from its ore.

• Metals can also be separated by using these compounds. The method of selective precipitation that separates the metals depends upon the solubility and stability of complexes.

• Metals can also be purified by using these compounds. When nickel reacts with carbon monoxide, tetracarbonylnockel complex is formed; this after distillation and thermal decomposition deposits the pure metal.

• These also find its application in electroplating. Articles are electroplated with the complexes of gold and silver [Ag(CN)2]–and [Au(CN)2].

IN PHOTOGRAPHY:

• In photography, the hyposolution in which complex of Ag is present [Ag(S2O3)2]3− , the developed film is fixed by washing in this