Question

Differentiate between homoleptic complex and heteroleptic complex.

Hint:

Remember: \[ \text{Homo} = \text{Same} \] \[ \text{Hetero} = \text{Different} \] Hence, Homoleptic \(\rightarrow\) Same ligand throughout Heteroleptic \(\rightarrow\) Different ligands present

Answer 1

Concept: Coordination compounds are formed when ligands donate lone pairs of electrons to a central metal atom or metal ion. Depending upon the nature and number of ligands attached to the metal centre, coordination compounds can be classified as homoleptic or heteroleptic complexes. This classification is based entirely on whether all ligands are identical or whether different kinds of ligands are present in the coordination sphere.

Step 1: Understanding Homoleptic Complexes. A coordination compound is called a homoleptic complex when only one kind of ligand surrounds the central metal ion. In such complexes, all ligands attached to the metal centre are identical. General representation: \[ [M(L)_n] \] where all ligands \(L\) are the same. Examples: \[ [Co(NH_3)_6]^{3+} \] \[ [Fe(CN)_6]^{4-} \] \[ [Ni(CO)_4] \] In each of these complexes, only one type of ligand is present around the central metal ion.

Step 2: Understanding Heteroleptic Complexes. A coordination compound is called a heteroleptic complex when two or more different types of ligands are attached to the central metal atom or ion. General representation: \[ [M(L)_x(L')_y] \] where \(L\) and \(L'\) are different ligands. Examples: \[ [Co(NH_3)_4Cl_2]^+ \] \[ [Pt(NH_3)_2Cl_2] \] \[ [Cr(H_2O)_4Cl_2]^+ \] These complexes contain more than one type of ligand.

Step 3: Tabular differentiation. \[ \begin{array}{|c|c|} \hline \textbf{Homoleptic Complex} & \textbf{Heteroleptic Complex} \\ \hline \text{Contains only one type of ligand} & \text{Contains two or more types of ligands} \\ \hline \text{All ligands are identical} & \text{Ligands are different} \\ \hline [Co(NH_3)_6]^{3+} & [Pt(NH_3)_2Cl_2] \\ \hline [Fe(CN)_6]^{4-} & [Co(NH_3)_4Cl_2]^+ \\ \hline \end{array} \]

Final Answer: \[ \boxed{ \begin{array}{l} \text{Homoleptic complex : Contains only one type of ligand.} \\ \text{Heteroleptic complex : Contains two or more different ligands.} \end{array} } \]