Question

Giving a suitable example for each, explain the following:
(i) Crystal field splitting
(ii) Linkage isomerism
(iii) Ambidentate ligand.

Answer 1

(i) Crystal field spliting: When the ligands approach the central metal ion, the electrons in the d-orbitals of central metal ion will be repelled by the lone pairs of the ligands. Because of these interactions the degeneracy of d orbitals of the metal ion is lost and these split into two sets of orbitals having different energies. This is known as crystal field splitting, e.g., for d⁴, configuration is t³_2g e¹_g  in the presence of weak field ligand.

(ii) Linkage isomerism: The isomers which have same molecular formula but differ in the linkage of ligand atom to the central metal atom are called linkage isomers, e.g.,

[Co(NH₃ )₅ NO₂ ]Cl₂ and [Co(NH₃)₅ONO]Cl₂

Pentaamminenitrito–N–Cobalt (III) chloride, pentaamminenitrito–O–Cobalt(III) chloride

(iii) Ambidentate ligand: A ligand which can bind to the central metal atom through any of the two donor atoms present in it is called ambidentate ligand, e.g., NO₂ can bind to metal either