Which property of Transition metals is responsible for complex formation ?

Question

Accepted Answer

Option 2, "Shows several oxidation states," is the correct answer because the ability of transition metals to form complexes is largely due to their variable oxidation states. This property allows transition metals to form stable complexes with various ligands. Here's why this is the case:

1. **Variable Oxidation States**: Transition metals can exhibit multiple oxidation states because they have partially filled d orbitals. This allows them to lose different numbers of electrons and form bonds with a variety of ligands, which is essential for complex formation. The presence of multiple oxidation states enables transition metals to adapt to different coordination environments and stabilize various complex structures.

2. **Explanation of Incorrect Options**:
   - **Option 1: Large size of transition metal cation**: While the size of the cation can influence the geometry and stability of a complex, it is not the primary reason for complex formation. The ability to form complexes is more directly related to the electronic configuration and oxidation states of the metal.
   - **Option 3: Absence of vacant (n-1)d orbitals**: This statement is incorrect because transition metals actually have partially filled d orbitals, which are crucial for bonding with ligands. The presence, not the absence, of these orbitals allows for the formation of coordinate covalent bonds in complexes.
   - **Option 4: Due to stable +2 oxidation state**: While some transition metals do commonly exhibit a +2 oxidation state, the ability to form complexes is not limited to this state. Transition metals can form complexes in various oxidation states, not just +2, which is why the variability in oxidation states (Option 2) is more relevant.

In summary, the ability of transition metals to show several oxidation states is the key factor that facilitates complex formation, as it allows them to interact with a wide range of ligands and form stable coordination compounds.