Which theory of bonding in coordination compounds treats the metal–ligand bond as ionic, arising purely from electrostatic interactions between the metal ion and the ligands?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Crystal Field Theory
Of the four bonding theories, only Crystal Field Theory (CFT) is a purely electrostatic model: the ligands act as point charges or point dipoles. The other three allow for orbital overlap or covalent character in the metal–ligand bond.
Why the other options are incorrect
Option (1) Valence Bond Theory — Incorrect. It explains the bond by hybridisation of the metal’s orbitals and their overlap with ligand orbitals that donate electron pairs, not by electrostatic attraction alone.
Option (2) Ligand Field Theory — Incorrect. It is one of the theories that take into account the covalent character of the metal–ligand bond, which CFT leaves out.
Option (3) Molecular Orbital Theory — Incorrect. It also takes the covalent character of the metal–ligand bond into account, so it does not treat the bond as purely ionic.
NCERT (2026-27 edition):
5.5.4 Crystal Field Theory – “The crystal field theory (CFT) is an electrostatic model which considers the metal-ligand bond to be ionic arising purely from electrostatic interactions between the metal ion and the ligand. Ligands are treated as point charges in case of anions or point dipoles in case of neutral molecules.”