Question

The increased tendency for complex formation in transition metals can be attributed to

• A. Small size of the cations
• B. High effective nuclear charge
• C. Availability of low-energy vacant orbitals
• D. All of these

Answer 1

The correct option is D All of these

The cations are relatively very small in size and possess high effective nuclear charge. Thus, they have a high positive charge density which facilitates the acceptance of lone pairs of electrons from ligands (molecules or ions which donate pair(s) of electrons to the central ion).
The transition metal cations have vacant inner d-orbitals which are of appropriate energy to accommodate a lone pair of electrons from the ligands. The bonds involved in the formation of complexes are coordinate or dative. Thus the name coordinate complexes.
The number of ligands attached to the central metal or ion is usually four or six. In other words, the coordination number of metal ion is usually four or six.