If we perform a qualitative analysis to identify the constituent ions present in both the compounds, Mohr's salt answers the presence of Fe²⁺, NH₄^+, and SO₄^2- ions, whereas the potassium ferrithiocyanate will not answer Fe³⁺ and SCN ions. We can infer that the double salts loose their identity and dissociate into their constituent simple ions in solutions, whereas the complex ion in coordination compound, does not loose its identity and never dissociate to give simple ions.

(i) A red blood corpuscle (RBC) is composed of heme group, which is Fe²⁺- Porphyrin complex. it plays an important role in carrying oxygen from lungs to tissues and carbon dioxide from tissues to lungs.
(ii) Chlorophyll, a green pigment present in green plants and algae, is a coordination complex containing Mg²⁺ as central metal ion surrounded by a modified Porphyrin ligand called corrin ring. It plays an important role in photosynthesis, by which plants converts CO₂ and water into carbohydrates and oxygen.
(iii) Vitamin B₁₂ (cyanocobalamin) is the only vitamin consist of metal ion. it is a coordination complex in which the central, metal ion is Co⁺ surrounded by Porphyrin like ligand.
(iv) Many enzymes are known to be metal complexes, they regulate biological processes. For example, Carboxypeptidase is a protease enzyme that hydrolytic enzyme important in digestion contains a zinc ion coordinated to the protein.

(i) The stability of a coordination complex is a measure of its resistance to the replacement of one ligand by another.
(ii) The stability of a complex refers to the degree of association between two species involved in an equilibrium.
(iii) Let us consider the following complex formation reaction
Cu²⁺ +4NH₃ ⇌ [Cu(NH₃)₄]^{2+
\(\beta =\frac { { \left[ { Cu\left( { NH }_{ 3 } \right) }_{ 4 } \right] }^{ 2+ } }{ \left[ { Cu }^{ 2+ } \right] { { \left[ { NH }_{ 3 } \right] }^{ 4 } } } \)}
(iv) So, as the concentration of [Cu (NH₃)₄]²⁺ increases the value of stability complexes also increases.
(v) Therefore the greater the value of stability constant greater is the stability of the complex.

Thus in metal carbonyls, electron density moves from ligand to metal through sigma bonding and from metal to ligand through pi bonding, this synergic effect accounts for strong M \(\longleftarrow \) CO bond in metal carbonyls.

(i) Coordination compounds which possess chirality exhibit optical isomerism similar to organic compounds.
(ii) The pair of two optically active isomers which are mirror images of each other are called enantiomers.
(iii) Their solutions rotate the plane of the plane polarised light either clockwise or anticlockwise and the corresponding isomers are called 'd' (dextrorotatory) and 'I'(levorotatory) forms respectively.
(iv) The octahedral complexes of type I [M(xx)₃]^n±, [M(xx)₂AB]^n± and [M(xx)₂B₂]^n± exhibit optical isomerism.
(v) Examples:
The optical isomers of [Co(en)₃]³⁺